为什么两个频率接近的音会听出“拍音”？
Why do two close frequencies produce a beating tone?
两个频率非常接近的音同时响，它们的声波会周期性地互相加强又抵消，听起来音量一强一弱地起伏，这就是拍音。
Two nearly equal frequencies interfere, periodically reinforcing and canceling, so the loudness pulses up and down—this wobble is a beat.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#拍音 #干涉 #频率
声学中的非线性项如何产生冲击波（如雷声、声爆）？
How do nonlinear terms create shock waves in acoustics?
声波大振幅时传播速度随局部压强升高而增大，波前追赶波后而变陡，最终破碎成不连续面（激波）；能量在很薄层内耗散，发出雷声般巨响与声爆。
At large amplitude the sound speed rises with local pressure, so wave crests catch up and steepen into a discontinuity (shock); energy dissipates in a thin layer, giving thunder-like booms and sonic cracks.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #激波 #非线性
主动噪声控制（ANC）如何利用波的干涉在局部区域抵消低频噪声？
How does active noise control use wave interference to cancel low-frequency noise in a local region?
ANC用麦克风采集原噪声，由控制器生成相位相反、振幅相等的反相声波，与原声波叠加产生相消干涉，使声压在该区域趋近于零。由于声波波长限制，ANC在低频（长波长）效果好，且仅在误差传声器附近有限空间有效。
ANC picks up the original noise with a microphone and a controller generates an anti-phase sound wave of equal amplitude; destructive interference drives the local sound pressure toward zero. Limited by wavelength, ANC works best at low frequencies and only in the small region near the error microphone.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Kuo & Morgan, Active Noise Control Systems: Algorithms and DSP Implementations（Wiley, 1996）
S. M. Kuo & D. R. Morgan, Active Noise Control Systems (Wiley, 1996)
#主动噪声控制 #相消干涉 #反相声波 #低频
什么是多普勒效应？
What is the Doppler effect?
多普勒效应指波源与观察者相对运动时，观察者接收到的频率发生变化的现象。火车驶近时汽笛音调变高、远离时变低，就是这一效应。
The Doppler effect is the change in observed frequency when the source and observer move relative to each other. A train whistle sounds higher as it approaches and lower as it recedes.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#多普勒效应 #频率 #相对运动
飞机超过音速时，为什么会产生“音爆”？
When a plane exceeds the speed of sound, why does it make a sonic boom?
声源快过声波时，后发的波前追上前发的，在机首堆成高压的锥形激波。这个锥面扫过地面时，就是一声巨响的音爆。
When the source outruns its own sound, later wavefronts pile onto earlier ones into a high-pressure conical shock at the nose. As that cone sweeps the ground, it is heard as a sonic boom.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#音爆 #激波 #马赫锥
吉他的弦上为什么能同时“存在”好几个波节？
Why can a guitar string show several nodes at once?
弦两端固定会形成驻波，只有波长能整除弦长的模式被允许，于是出现基频和一系列泛音，节点位置固定不动。不同泛音叠加决定了音色。
With fixed ends, the string forms standing waves; only modes whose wavelengths divide the string are allowed, giving a fundamental and overtones with fixed nodes. Their mix sets the timbre.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》
The Feynman Lectures on Physics
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#驻波 #泛音 #节点
为什么房间大小会影响驻波与听感死点？
Why does room size affect standing waves and dead spots?
平行墙面间若声程为半波长的整数倍会形成驻波（房间模式），某些频率在某些位置被抵消或加强，造成听感上的峰谷与死点；声学设计用扩散体打破规则反射来缓解。
Between parallel walls, half-wavelength resonances form standing waves (room modes), boosting or canceling specific frequencies at given spots; diffusers break regular reflections to reduce them.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #驻波 #房间声学
消声器的驻波与阻抗匹配怎样减弱排气噪声？
How do muffler standing waves and impedance matching cut exhaust noise?
消声器用扩张腔与穿孔管形成声学低通或抗谐振：在目标频带制造与来波反相的反射（阻抗失配）或耗散性多孔吸声，使排气噪声在出口被大幅衰减。
Mufflers use expansion chambers and perforated tubes to create anti-resonant reflections (impedance mismatch) or dissipative porous absorption at target bands, attenuating exhaust noise at the outlet.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #消声器 #阻抗
Bragg 散射型声子晶体在千赫兹以下很难打开带隙,局域共振结构是怎样绕开这个限制的?
Bragg-scattering phononic crystals struggle to open band gaps below kilohertz frequencies; how do locally resonant structures get around this limit?
Bragg 机制要求波长与晶格常数同量级,音频低频对应的米级周期在工程上无法实现。局域共振单元在其固有频率附近与基体强耦合,使等效动态质量密度或等效模量变为负值,于是在远小于波长的晶格尺寸上也能打开完全带隙。带隙位置由共振子质量、刚度和填充率决定,基本与周期大小解耦。
The Bragg mechanism demands wavelengths comparable to the lattice constant, which would mean meter-scale periodicity at low audio frequencies. Locally resonant units couple strongly to the matrix near their natural frequency, driving the effective dynamic mass density or modulus negative and opening complete gaps on deeply subwavelength lattices. Gap positions are set by resonator mass, stiffness, and filling fraction, essentially decoupled from the period itself.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
刘正猷等发表于《Science》290 卷 1734 页的局域共振声学材料论文,低频隔振任务 ; 另见: Z. Liu et al., Science 290, 1734 (2000) locally resonant sonic materials, low-frequency vibration isolation task
Z. Liu et al., Science 290, 1734 (2000) locally resonant sonic materials, low-frequency vibration isolation task ; see also: 刘正猷等发表于《Science》290 卷 1734 页的局域共振声学材料论文,低频隔振任务
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1126/science.289.5485.1734：Locally Resona
#声子晶体 #局域共振带隙
水中气泡的米纳尔特共振频率是什么？它为何让微小气泡成为水下声场的主导散射与吸收体？
What is the Minnaert resonance frequency of a gas bubble, and why does it make tiny bubbles dominant scatterers and absorbers of underwater sound?
气泡像一个振子：可压缩气体充当弹簧，周围水的惯性充当质量，共振频率f≈(1/2πR)√(3γP0/ρ)，与半径成反比。毫米级气泡共振在千赫兹量级，远低于同尺寸刚性球的瑞利散射预期；近共振时散射截面可比几何截面大几个数量级，因此舰船尾流和生物气泡层会显著衰减声呐信号，雨滴入海的气泡也构成海洋环境噪声源。
A bubble acts as an oscillator: the compressible gas supplies the spring and the inertia of the surrounding water supplies the mass, giving f≈(1/2πR)√(3γP0/ρ), inversely proportional to radius. Millimetre-sized bubbles resonate at kilohertz frequencies, far below what Rayleigh scattering from a rigid sphere of that size would imply, and near resonance the scattering cross-section can exceed the geometric cross-section by orders of magnitude. Ship wakes and biological bubble layers therefore strongly attenuate sonar, and bubbles from raindrops hitting the sea are a major source of ocean ambient noise.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
Minnaert,《XVI. On musical air-bubbles and the sounds of running water》,Philosophical Magazine,1933 (DOI: 10.1080/14786443309462277)
Minnaert, 'XVI. On musical air-bubbles and the sounds of running water', Philosophical Magazine, 1933, DOI: 10.1080/14786443309462277
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1080/14786443309462277
#气泡共振 #声散射 #海洋环境噪声
救护车鸣笛靠近时音调变高、远离时变低，为什么？
Why does an ambulance siren sound higher as it approaches and lower as it leaves?
这是多普勒效应：声源靠近时波前被压缩、波长变短、频率变高；远离时被拉开、频率变低。我们据此判断车在靠近还是走远。
This is the Doppler effect: as the source approaches, wavefronts compress to shorter wavelengths and higher pitch; as it leaves, they stretch and the pitch drops. It tells us the siren is coming or going.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#多普勒效应 #频率 #音调
医学超声成像基于什么物理原理，为何能无损地观察体内组织？
On what physical principle does medical ultrasound imaging rely, and why can it image internal tissue non-invasively?
超声探头发射高频声波（通常1至15 MHz），遇到不同声阻抗的组织界面时发生反射，回波经压电换能器转为电信号并按时间延迟重建为断面图像。因其使用机械能而非电离辐射，对人体基本无损伤。
An ultrasound probe emits high-frequency sound (typically 1 to 15 MHz); reflections occur at tissue interfaces of differing acoustic impedance, and the echoes are converted by piezoelectric transducers into electrical signals reconstructed by time delay into cross-sectional images. Using mechanical energy rather than ionizing radiation, it is essentially non-damaging.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Wells, Biomedical Ultrasonics（Academic Press, 1977）
P. N. T. Wells, Biomedical Ultrasonics (Academic Press, 1977)
#超声成像 #声阻抗 #压电换能器 #回波
为什么士兵过桥时要便步而不是齐步走？
Why do soldiers break step rather than march in rhythm across a bridge?
若步伐频率接近桥的固有频率，会不断“叠加”能量引发共振，振幅大到可能损坏桥。便步让能量分散，避免同频激发。
If the march matches the bridge's natural frequency, energy builds by resonance and the swing can grow enough to damage it. Breaking step spreads the energy and avoids driving that frequency.
难度 进阶 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
L. E. Kinsler、A. R. Frey、A. B. Coppens 与 J. V. Sanders 著《Fundamentals of Acoustics》（声学基础）
L. E. Kinsler, A. R. Frey, A. B. Coppens & J. V. Sanders, Fundamentals of Acoustics
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471847892 (2000)
#共振 #固有频率 #振幅
超声波有什么用处？
What are ultrasonic waves used for?
超声波是频率高于人耳上限的声波，方向性好且能穿透某些材料。医学上的 B 超和工业探伤都利用超声波来成像或检测缺陷。
Ultrasound is sound above the human hearing range, with good directionality and the ability to penetrate some materials. Medical ultrasound scans and industrial flaw detection both use it to image or find defects.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#超声波 #频率 #成像
医院用超声波怎么看到肚子里的宝宝？
How does ultrasound let doctors see a baby in the womb?
探头发出听不见的高频声波，碰到不同组织会反射回来，电脑把回声强弱画成图像，就能看到宝宝的样子。
A probe sends high-frequency sound that reflects off different tissues; a computer turns the echoes into an image of the baby.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
Kinsler、Frey、Coppens 与 Sanders，《声学基础》（第4版）
Kinsler, Frey, Coppens & Sanders, 'Fundamentals of Acoustics' (4th ed.)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471847892 (2000)
#超声波 #成像 #医学
声波的多普勒效应与光波有何不同，为何需要介质参考系？
How does the Doppler effect for sound differ from that for light, and why does a medium reference frame matter?
声波是介质中的机械波，其频率变化依赖声源与观察者相对介质的速度，因此相对运动需分别计入二者对介质的运动。光作为相对论性电磁波则只需源与观察者的相对速度，无需介质，由洛伦兹变换给出。
Sound is a mechanical wave in a medium, so its frequency shift depends on the source's and observer's velocities relative to the medium, treated separately. Light, as a relativistic electromagnetic wave, depends only on the relative velocity of source and observer via Lorentz transformation and needs no medium.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第1卷（声波）
The Feynman Lectures on Physics vol.1 (sound waves)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#多普勒效应 #声波 #介质 #相对运动
为什么空房间说话会有回响？
Why does an empty room make your voice echo?
空房间里硬墙壁把声音反复反射，家具和地毯少、吸音差，声音叠在一起形成回响（混响）。
Bare hard walls reflect sound repeatedly; with little furniture to absorb it, the reflections overlap and linger as reverberation.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#混响 #反射 #吸音
乐器是怎么发出不同音调的？
How do musical instruments produce different pitches?
声音的高低由频率决定：弦更短更紧或管更短，振动更快、频率更高，音调就更尖；反之更低沉。
Pitch depends on frequency: shorter or tighter strings and shorter tubes vibrate faster (higher frequency), giving higher notes; longer ones give lower notes.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#音调 #频率 #乐器
音调和频率有什么关系？
How are pitch and frequency related?
音调的高低由声波的频率决定，频率越高声音越尖，频率越低声音越沉。人耳通常能听到 20 赫兹到 20000 赫兹之间的声音。
Pitch is set by a sound wave's frequency: higher frequency sounds sharper, lower frequency sounds deeper. The human ear typically hears from 20 to 20,000 hertz.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#音调 #频率 #赫兹
两列相干声波叠加时，为何某些位置始终加强、某些位置始终减弱？
When two coherent sound waves superpose, why are some positions always reinforced and others always weakened?
相干声波具有固定相位差，叠加后声压振幅按相位差呈稳定分布：同相处（相位差为2π整数倍）压强振幅相加，反相处（相差π的奇数倍）相互抵消。这种稳定的强弱分布在空间中形成驻波或干涉图样。
Coherent sound waves have a fixed phase difference, so their superposition gives a stable amplitude pattern: in-phase points (phase difference of integer multiples of 2π) add, while anti-phase points (odd multiples of π) cancel. This stable pattern forms standing waves or interference fringes.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《费曼物理学讲义》第1卷（波）
The Feynman Lectures on Physics vol.1 (waves)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-0-7382-0298-3 (2006 Pearson 版，原始版为1963-65 Addis
#声波干涉 #相干 #相位差 #驻波
固体物理中的「声子」是什么，它如何同时解释晶格热容与热传导？
What is a phonon in solid-state physics, and how does it explain both lattice heat capacity and thermal conduction?
声子是晶格集体振动的量子化准粒子，分为声学支与光学支。在低温下声子激发受玻色-爱因斯坦统计限制，使热容按德拜 T³ 律下降；而声子在晶格中的扩散与散射则承载着固体的主要热传导。
A phonon is the quantized quasiparticle of collective lattice vibrations, with acoustic and optical branches. At low temperature phonon excitation is limited by Bose-Einstein statistics, making heat capacity follow the Debye T³ law; phonon diffusion and scattering also carry most of a solid's thermal conduction.
难度 进阶 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-10-04 · 2 条独立证据
来源 · Source
Kittel, Introduction to Solid State Physics（第8版, Wiley, 2004）
C. Kittel, Introduction to Solid State Physics (8th ed., Wiley, 2004)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471490241 (2005) · 核验依据 2 ISBN 9780030839931 (2022)
#声子 #晶格振动 #德拜模型 #热传导
蝙蝠用的超声波和地震前的次声波差在哪？
How do bats' ultrasound and pre-quake infrasound differ?
人耳约能听 20 Hz–20 kHz；超声波频率高于上限、波长短可精细测距（蝙蝠回声定位）；次声波低于下限、传得极远却听不见（地震、海啸前常出现）。
Human hearing spans about 20 Hz–20 kHz; ultrasound is above that, with short waves good for fine ranging (bat echolocation), while infrasound is below it, traveling vast distances yet unheard (often before quakes or tsunamis).
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#超声波 #次声波 #频率
为什么把耳朵贴在铁轨上能更早听到远处火车？
Why does pressing an ear to a rail let you hear a train sooner?
固体（钢）中声速约5000 m/s，远高于空气中的约340 m/s，且能量衰减慢、传得远；所以沿铁轨的振动比空气传声更早到达。
Sound in steel travels ~5000 m/s versus ~340 m/s in air and decays slower, so rail vibrations arrive much earlier than airborne sound.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #固体传播 #速度
闭着眼也能听出声音来自左边还是右边，人耳靠的是什么线索？
Even with eyes closed you can tell whether a sound comes from the left or right—what cues does the ear use?
双耳定位主要靠两条线索：同一声源到达两耳的时间差，以及因头部遮挡造成的两耳声强差（尤其对高频明显）。大脑综合这些微小差异，就能判断声源的左右方位。低频主要靠时间差，高频更多靠强度差。
Binaural localization relies mainly on two cues: the tiny time difference of a sound reaching the two ears, and the intensity difference caused by the head's shadow, especially at high frequencies. The brain combines these small differences to judge left–right direction. Low frequencies use timing, high frequencies lean on loudness.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-11-04
来源 · Source
W. M. Hartmann,《How We Localize Sound》,Physics Today,1999 (DOI: 10.1063/1.882727)
W. M. Hartmann, 'How We Localize Sound', Physics Today, 1999, DOI: 10.1063/1.882727
独立核验依据 · Independent verification: 核验依据 1 Crossref DOI 10.1063/1.882727
#双耳定位 #时间差 #声强差
为什么对着山崖喊话会听到回声？
Why do you hear an echo off a cliff?
声音像球一样碰到坚硬崖壁被反射回来；若你与崖壁距离够远（通常大于约17米，使回程大于0.1秒），返回的声波与直接声分得开，就听成回声。
Sound reflects off a hard cliff like a ball; if the cliff is far enough (>~17 m, so the return exceeds 0.1 s) the delayed wave is heard separately as an echo.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #回声 #反射
什么是共振？
What is resonance?
当外界驱动力的频率接近物体的固有频率时，物体的振动幅度会急剧增大，这叫共振。军人过桥时便步走就是为了避免步伐频率与桥的固有频率一致引发危险共振。
When an external driving frequency approaches an object's natural frequency, its vibration amplitude grows sharply; this is resonance. Soldiers march out of step on bridges to avoid matching the bridge's natural frequency and causing dangerous resonance.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#共振 #固有频率 #振动
声音在固体、液体和气体中的传播速度由哪些物理量决定，为何固体中最快？
Which physical quantities determine sound speed in solids, liquids, and gases, and why is it fastest in solids?
声速由介质的体积模量与密度决定 c = √(K/ρ)，在固体中还需考虑剪切模量。固体原子间结合强、可恢复形变大且密度适中，刚度远高于气体，故纵波声速通常最大，气体因极低刚度而最慢。
Sound speed is set by the bulk modulus and density, c = √(K/ρ), with shear modulus also relevant in solids. Solids have strong interatomic bonds and high stiffness with moderate density, so longitudinal sound is usually fastest; gases are slowest due to very low stiffness.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
Landau & Lifshitz, Fluid Mechanics（第2版, Butterworth-Heinemann, 1987）
L. D. Landau & E. M. Lifshitz, Fluid Mechanics (2nd ed., Butterworth-Heinemann, 1987)
#声速 #体积模量 #密度 #介质
超音速飞机飞过时「音爆」是怎么产生的？
How does a sonic boom arise when a supersonic jet flies past?
当飞机速度超过声速，它比自己发出的声波跑得还快，前方声波被挤压、叠加成一道高压力的「激波」（马赫锥）。飞机掠过时，这道激波扫过地面，气压骤升又骤降，人耳就听到两声巨响似的「砰」——即音爆。它只在超音速时存在，亚音速则不会累积成激波。
When an aircraft exceeds the speed of sound it outruns its own sound waves, which pile up ahead into a high-pressure shock wave (the Mach cone). As the plane passes, the cone sweeps the ground and pressure jumps up then down, sounding like a double bang—the sonic boom. It exists only supersonically; subsonic flight never builds such a shock.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#音爆 #激波 #马赫锥
超声探伤中为什么常用斜探头让钢件里传播的是横波,而不是直接打纵波进去?
In ultrasonic flaw detection, why do inspectors often use angle-beam probes to send shear waves into steel rather than longitudinal waves directly?
同频率下钢中横波速度约为纵波的一半,波长更短,对小缺陷的分辨能力更强。横波的切向振动分量对与声束成一定角度取向的裂纹类缺陷回波也更敏感。借助有机楔块与钢界面的折射,还能把声束偏折到有利方向,避开几何反射面的干扰。
At the same frequency the shear-wave speed in steel is roughly half that of longitudinal waves, so the wavelength is shorter and small defects resolve better. The transverse particle motion also returns stronger echoes from crack-like flaws angled across the beam. Refraction at the wedge-to-steel interface further lets inspectors steer the beam away from spurious geometric reflectors.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：著录仅给书名，无版次与年份；同一书名常对应多个版次，不臆测具体版本。
《无损检测手册·超声卷》,焊缝缺陷定量评定任务
ASNT Nondestructive Testing Handbook, 3rd ed., Vol. 7: Ultrasonic Testing, weld defect sizing task
#超声波检测 #横波斜探头
音乐厅的混响时间是怎么定义的,设计师靠什么把它调到想要的长短?
How is the reverberation time of a concert hall defined, and what do designers adjust to set it where they want?
混响时间指声源停止后室内声能衰减 60 dB 所需的时间,赛宾公式给出 T = 0.161 V/A,V 是厅堂体积,A 是总吸声量。设计上靠控制每座容积、观众席吸声、可变吸声板与墙面木饰来调节:语言用厅希望 1 秒上下,交响乐厅通常取 1.8 到 2.1 秒以保证声音丰满。
Reverberation time is how long sound energy takes to decay 60 dB after the source stops; Sabine's formula gives T = 0.161 V/A, with V the hall volume and A the total absorption. Designers tune volume per seat, audience absorption, variable panels, and wood finishes: speech rooms aim near 1 s, while symphony halls take about 1.8 to 2.1 s for warmth and fullness.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
白瑞纳克《音乐厅与歌剧院》,厅堂音质评价任务
L. Beranek, Concert Halls and Opera Houses, hall acoustics assessment task
独立核验依据 · Independent verification: 核验依据 1 CROSSREF 标识 10.1007/978-0-387-21636-2：Concert Halls and
#建筑声学 #混响时间
医用超声探头必须先涂一层耦合剂再贴合皮肤，如果探头与皮肤之间留有空气会发生什么，背后的声学原理是什么？
An ultrasound probe must be pressed onto the skin through a layer of coupling gel — what happens if a pocket of air intervenes, and which acoustic principle explains it?
空气的声阻抗仅为软组织的万分之几量级，界面反射系数趋近于一，入射声能几乎全被弹回，成像信号无从谈起。耦合剂的阻抗介于压电晶体与皮肤之间，把单一陡峭的分界面替换为两级渐变的过渡，透射系数因此大幅上升。这与光学增透膜的思路一致，都是在失配介质之间插入匹配层。
Air has an acoustic impedance only on the order of one ten-thousandth of that of soft tissue, so the interface reflection coefficient approaches unity and almost no acoustic energy enters the body. Coupling gel presents an intermediate impedance that replaces the single abrupt boundary with graded transitions, sharply increasing transmission. The strategy parallels antireflection coatings in optics: insert matching layers between mismatched media.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
F. W. Kinsler、A. R. Frey、A. B. Coppens 与 J. V. Sanders 合著《Fundamentals of Acoustics》第4版，Wiley
F. W. Kinsler, A. R. Frey, A. B. Coppens, and J. V. Sanders, Fundamentals of Acoustics, 4th ed., Wiley
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780471847892 (2000)
#声阻抗匹配 #界面反射
深海声道为什么能让低频声波横跨整个大洋而衰减很少？
Why can low-frequency sound traverse an entire ocean basin inside the deep sound channel while suffering little attenuation?
海水声速随降温而减小、随加压而增大，两者在中纬度约千米深处相互抵消形成极小值，即SOFAR声道轴。偏离轴线的声线因折射不断弯回低速层，如同光被约束在光纤纤芯中，能量主要只沿水平方向扩散。几何扩展随距离一次方而非平方增长，加上低频海水吸收很弱，信号因此能够远距离传播。
Sound speed in seawater drops as temperature falls and climbs as pressure rises; the two trends cancel near a depth of a kilometer at mid latitudes, forming the SOFAR channel axis. Rays straying from the axis refract back toward this low-speed layer much as light stays confined in a fiber core, so energy spreads mainly horizontally. Geometric spreading then grows linearly rather than quadratically, and low-frequency absorption in seawater is weak, enabling basin-scale propagation.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
H. Medwin与C.S. Clay，《Fundamentals of Acoustical Oceanography》，Academic Press（1998）
H. Medwin and C.S. Clay, Fundamentals of Acoustical Oceanography, Academic Press (1998)
独立核验依据 · Independent verification: 核验依据 1 ISBN 9780124875708 (1998)
#水声学 #折射波导
声音在空气中几公里外就听不见了，为什么低频声音却能在海水中传出数千公里？
Sound fades within a few kilometres in air, so why can low-frequency sound travel thousands of kilometres through the ocean?
海水声速由温度、盐度与压强共同决定：上层水温随深度下降使声速渐减，约千米深处出现极小值，更深处压强占优又令声速回升。声线总向低速区弯折，于是在这条“深海声道”轴上下振荡而被捕获，宛如天然光纤；声能仅作柱面扩散而非球面扩散，损耗大减，低频声得以横跨大洋，鲸群的远距歌唱正依赖此通道。
Seawater sound speed depends on temperature, salinity, and pressure: falling temperature slows sound down to a minimum near one kilometre deep, below which pressure dominates and speeds it up again. Rays always bend toward slower water, so they oscillate about this deep sound channel axis and stay trapped, like light in a natural optical fiber; energy then spreads cylindrically rather than spherically, cutting losses so drastically that low-frequency sound crosses whole ocean basins — the basis of whale long-range songs.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
R. J. Urick《水声原理》第3版，Peninsula Publishing（1983年）
R. J. Urick, Principles of Underwater Sound, 3rd ed., Peninsula Publishing, 1983
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL5462762W：Principles of underwate
#深海声道 #声速剖面 #声折射 #海洋声学
为什么说人耳对极微弱声音的高灵敏度和精细的频率分辨，靠的不是被动的机械传导，而是耳蜗自身的主动放大？
Why is the ear's extreme sensitivity to faint sounds and its fine frequency discrimination credited not to passive mechanics but to an active amplifier built into the cochlea?
不是。耳蜗有一套主动机制：感受声波的信号主要由单排内毛细胞转导，外围三排外毛细胞则借助膜蛋白prestin随电压伸缩，向行波注入机械能，可把弱声下的基底膜响应提高几十倍乃至上百倍。Gold在1948年就预言了这一主动过程，后来发现的耳声发射正是它泄漏回耳道的副产品。有了主动供能，人耳对微弱声音才既灵敏又能精细分辨频率。
No. The cochlea runs an active mechanism: sound signals are transduced mainly by the single row of inner hair cells, while the three outer rows act as motors. Their membrane protein prestin lets the cells lengthen and shorten with voltage, injecting mechanical energy into the traveling wave and boosting the basilar membrane's weak-sound response by tens to hundreds of times. Thomas Gold predicted this active process in 1948, and the otoacoustic emissions later detected in the ear canal are its leaked by-product. This powered feedback is what makes hearing at threshold both sensitive and finely tuned in frequency.
难度 进阶 · 适合 大众
CC BY 4.0 · 来源待核验 · Source pending review
来源 · Source
出处备注：此条未指向带版次的可引用著作（通识性内容、机构文件或未展开的英文书名），本库不提供独立书目出处；如需精确引用，需由编辑补全具体篇目与版次。
T. Gold,Proceedings of the Royal Society B,1948；J. Zheng et al.,Nature,2000
T. Gold, Proceedings of the Royal Society B, 1948; J. Zheng et al., Nature, 2000
#听觉 #耳蜗 #主动放大
回声是怎么产生的？
How is an echo produced?
声音遇到墙壁等障碍物会反射回来，如果反射声比原声晚到 0.1 秒以上，人耳就能分辨出回声。空旷的山谷和大厅里最容易听到回声。
Sound reflecting off a wall or cliff returns to the listener; if the reflected sound arrives more than about 0.1 second after the original, the ear hears it as an echo. Open valleys and halls produce them most easily.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#回声 #反射 #声波
声音是怎么传播到我们耳朵里的？
How does sound travel to our ears?
物体振动会推动周围空气形成疏密相间的声波，声波通过空气等介质传到耳朵，使鼓膜振动并被大脑识别为声音。声音不能在真空中传播。
A vibrating object pushes surrounding air into alternating compressions and rarefactions, forming sound waves that travel through a medium to the ear and make the eardrum vibrate. Sound cannot travel through a vacuum.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声音 #振动 #声波
为什么我们听不到狗哨的声音？
Why can't we hear a dog whistle?
狗哨发出的是超声波，频率高于人耳能听见的上限（约 2 万赫兹），所以人听不到，狗却听得到。
A dog whistle emits ultrasound above the human hearing limit (~20 kHz), so people can't hear it, but dogs can.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#超声波 #频率 #听觉
为什么我们能听到声音？
How do we hear sounds?
物体振动推动空气形成声波，传入耳朵刺激鼓膜与神经。
Vibrations make sound waves in air that shake the eardrum and nerves.
难度 入门 · 适合 小学高段(9-12)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#声波 #振动 #耳朵
弹吉他时，为什么按住琴弦越靠后（有效长度越短），发出的音就越高？
When playing guitar, why does pressing the string shorter make the note higher?
弦振动的基本频率与其长度成反比，弦越短，来回振动一次越快，频率越高，听感上音就越尖。所以同一根弦，按在不同品丝上改变有效长度，就能奏出不同音高。这也是所有弦乐器定音的基础。
The fundamental frequency of a vibrating string is inversely proportional to its length; a shorter string completes each back-and-forth vibration faster, giving a higher frequency and a higher pitch. That is why pressing a string at different frets changes the note. It is the basis of tuning for all string instruments.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
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R. A. Serway & J. W. Jewett,《Physics for Scientists and Engineers》(第9版),第18章(驻波)
R. A. Serway & J. W. Jewett, 'Physics for Scientists and Engineers' (9th ed.), Ch.18 (Standing waves)
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#弦振动 #驻波 #基频
为什么大声喊叫时能看到对面人的嘴在动却听不清？
Why can you see someone's lips move but not hear clearly when far away?
光跑得极快又走直线，眼睛早早看到动作；声音跑得慢多了还会被风、距离削弱，到你耳朵时已经太小太散，所以看得到却听不清。
Light is super-fast and goes straight so your eyes catch motion early; sound is slower and weakens with distance, arriving too faint to understand.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #光声对比 #距离
吉他弦为什么会发出固定音高，而不是乱响？
Why does a guitar string produce a fixed pitch instead of a random noise?
拨动琴弦时，只有那些能在弦长内恰好形成整数个「驻波」的振动模式被保留下来——波峰波谷被两端固定点锁住，来回反射叠加成稳定的形状。不同模式对应不同频率（基频和它的整数倍泛音），所以我们听到清晰的音高。驻波也出现在管乐器和鼓面上。
When you pluck a string, only vibrations that fit a whole number of 'standing waves' along its length survive—their peaks and nodes are pinned by the fixed ends and reinforce into a stable shape. Each mode has a frequency (the fundamental and its integer harmonics), giving a clear pitch. Standing waves also appear in wind instruments and drumheads.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-11-03
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T. D. 罗辛《声学》关于弦振动与驻波的章节
T. D. Rossing, 'The Science of Sound', on string vibration and standing waves
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL83263W：The science of sound（首版 1
#驻波 #谐波 #共振频率
为什么敲一下空瓶子会嗡的一声？
Why does tapping an empty bottle go boom?
瓶里的空气柱被敲动后来回振动，像一个小鼓，发出特定音调；瓶中空气越多、瓶子越大，声音越低沉。
The air column in the bottle vibrates back and forth like a tiny drum, making a tone; more air or a bigger bottle gives a deeper sound.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #共振 #空气柱
为什么先看到闪电，后听到雷声？
Why do we see lightning before we hear thunder?
光跑得比声音快得多。闪电和雷声同时发生，但光几乎瞬间到达，声音要慢吞吞走好一会儿。
Light travels much faster than sound. The flash and the boom happen together, but light arrives almost instantly while sound takes its time.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 3 条独立证据
来源 · Source
Halliday、Resnick 与 Walker，《物理学基础》（第10版）
Halliday, Resnick & Walker, 'Fundamentals of Physics' (10th ed.)
独立核验依据 · Independent verification: 核验依据 2 angusrobertson.com.au
#光速 #声速 #雷电
太空里为什么听不到声音？
Why can't you hear sound in space?
声音靠空气、水等介质里的振动传播，太空几乎是真空，没有东西振动传声。所以太空里再大的爆炸也是“无声”的。
Sound travels by vibrations in a medium like air or water; space is nearly empty, with nothing to carry the vibration. So even a huge explosion in space makes no sound.
难度 入门 · 适合 幼儿(3-6)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声音 #真空 #介质
为什么救护车开近时警笛听起来更尖，开远后变低沉？
Why does an ambulance siren sound higher as it approaches and lower as it leaves?
这是多普勒效应：声源朝你运动时，它发出的声波被压缩，到达你耳中的波长变短、频率变高，于是音调更尖；远离时声波被拉开，频率变低、音调下沉。同样的原理也用于雷达测速和天文学中测星系退行（光的多普勒红移）。它由克里斯蒂安·多普勒1842年提出。
This is the Doppler effect: as the source moves toward you, its sound waves compress, reaching your ear with shorter wavelength and higher frequency, so the pitch rises; moving away stretches them, lowering the frequency and pitch. The same idea is used in radar speed guns and in astronomy to measure receding galaxies (optical redshift). Christian Doppler proposed it in 1842.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-11-03
来源 · Source
C. 多普勒 1842 年关于光与声频率变化的论文；T. D. 罗辛《声学》
C. Doppler (1842) paper on frequency shift; T. D. Rossing, 'The Science of Sound'
独立核验依据 · Independent verification: 核验依据 1 OPENLIBRARY 标识 /works/OL83263W：The science of sound（首版 1
#多普勒效应 #频率 #波长
为什么声音在水里比在空气中传得快？
Why does sound travel faster in water than in air?
声速取决于介质的多大劲（弹性）和多大密度；水虽密但极难压缩、弹性大，综合下来声速约1500 m/s，远快于空气里的约340 m/s。
Speed depends on stiffness over density; water is hard to compress, so despite its density sound reaches ~1500 m/s vs ~340 m/s in air.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#声学 #声速 #介质
用手指沾点水轻轻摩擦酒杯的杯口，为什么杯子会发出悠长而纯净的嗡鸣声？
Why does lightly rubbing a wet finger around a wine glass rim make it sing a long, pure tone?
手指沿杯口滑动时的“粘—滑”摩擦不断向杯壁输入能量，激起杯沿的弯曲振动模态——最低模态是带四个节点的“椭圆化”驻波。该模态频率由杯壁几何与材料决定、相当稳定，所以听到纯净持续的乐音；往杯里加水会让频率明显降低。玻璃琴就是靠同一机制发声的。
Stick–slip friction between the sliding wet finger and the rim keeps pumping energy into the glass, exciting a bending mode of the rim—the lowest one being an 'ovalling' standing wave with four nodes. That mode's frequency is fixed by the glass geometry and material and is quite stable, so the tone is pure and sustained; adding water to the glass lowers the pitch noticeably. The glass harmonica sounds by exactly the same mechanism.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-04
来源 · Source
A. P. French,《In Vino Veritas: A Study of Wineglass Acoustics》,American Journal of Physics 51,688(1983)
A. P. French, 'In Vino Veritas: A Study of Wineglass Acoustics', American Journal of Physics 51, 688 (1983)
独立核验依据 · Independent verification: 核验依据 1 DOI 10.1119/1.13147
#共振 #驻波 #杯沿振动
为什么太空中没有声音？
Why is there no sound in space?
声音需要空气、水等物质作为传播的介质，而太空几乎是真空，没有粒子来传递振动。所以在真空中即使有爆炸也不会发出声音。
Sound needs a material medium such as air or water to carry its vibrations, but space is nearly a vacuum with no particles to transmit them. So even an explosion in space makes no sound.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#真空 #介质 #声波
山谷里大喊为什么会听到回声？
Why do you hear an echo when you shout in a valley?
声音碰到远处的山崖被反射回来，若比原声晚到约 0.1 秒以上，耳朵就能分开两次，听成回声。太近的反射会混成混响而非分明回声。
Sound bounces off a far cliff and returns; if it arrives more than about 0.1 s after the original, your ear hears it separately as an echo. Too close, and it blends into reverberation.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-08-23 · 2 条独立证据
来源 · Source
Serway & Jewett,《Physics for Scientists and Engineers》第9版,Cengage Learning,2013
R. A. Serway and J. W. Jewett, Physics for Scientists and Engineers, 9th ed., Cengage Learning, 2013
独立核验依据 · Independent verification: 核验依据 2 ISBN 978-1-337-55327-8
#回声 #反射 #声波
对着大山喊一声,为什么能听到自己的回声?
Why can you hear your own echo when you shout at a mountain?
声音向前跑,碰到大山或高墙会被弹回来,这个现象叫反射。弹回来的声音就是回声。空旷的山谷里,回声要多跑一段路才回到耳朵,比喊声慢一点,听起来就像有人学你说话。教室的墙太近太软,回声混在喊声里,就不容易听出来啦。
Sound rushes forward and bounces back when it hits a big mountain or wall; bouncing back is called reflection. The bounced-back sound is an echo. In a wide valley the echo travels an extra stretch before returning, arriving a little late, so it sounds like someone copying you. In a classroom the walls are too close and too soft, so the echo hides inside your shout.
难度 入门 · 适合 小学低段(6-8)
CC BY 4.0 · 已核验 · Verified 2026-10-03 · 2 条独立证据
来源 · Source
《十万个为什么》第六版物理分册,少年儿童出版社,2013
Ten Thousand Whys: Physics volume, 6th ed., Juvenile and Children Publishing House, 2013
独立核验依据 · Independent verification: 核验依据 1 ISBN 978-7-5324-9328-9 · 核验依据 2 ISBN 9787532493289
#回声 #声的反射 #声音传播