Sound (images) – produced by a vibrating object. The vibrating object may be one’s vocal cords, the diaphragm of a speaker, the vibrations of a drumhead, or a plucked guitar string.

A sound wave is characterized by its speed, its wavelength and its amplitude. The speed of sound depends on the medium through which the sound travels and also depends on temperature and not on the air pressure. The speed of sound is about 340 m/s in air and 1500 m/s in water. The wavelength is the distance from one wave peak to the next.

Acoustics – a branch of physics and is the study of sound, mechanical waves in gases, liquids, and solids.

Acoustic engineering is the study of how sound is generated and measured by loudspeakers, microphones, sonar projectors, hydrophones, ultrasonic transducers, sensors, Electro Acoustics, and other topics. The application of acoustics in technology is called acoustical engineering.

Sound reproduction

  • Loudspeakers are a key part of any hi-fi system. Arguably, loudspeakers have a greater impact on the quality of reproduced sound than any other component in an audio system. It is relatively straightforward to design a loudspeaker that relays sound in a way that we can hear and enjoy. But the real challenge lies in delivering one that can convince a listener that they are at a live venue, listening to the ‘real thing’.


  • Real Clarity – the hearing aid for people who need help hearing a conversation in a noisy room. The app adjusts its algorithms to optimize its audio enhancements. People who have a more precise diagnosis of hearing deficiencies can set the app’s parameters manually. Put in your earbuds, set the mobile device down in front of you, and it will raise the volume on the conversation and lower the volume on the noise around you.

What’s the problem?
Can you hear me in the back – A concert hall must enable the musicians to achieve their desired dynamic, from the quietest solo to the loudest fanfare.

  • Ask – Listeners should be a close to the orchestra as possible. How can seats be place to reduce the space between the orchestra and the listeners?
  • Imagine – The interior surfaces of the hall should be hard to ensure that sound energy is not absorbed and lost. Listeners should have a line of sight to the orchestra so the sound can travel unobstructed. How can everyone in the audience have a sight line to the orchestra? What are seating arranges that provide a clear view of the action in other venues like sports stadiums? Can these be adapted for a concert hall?
  • Plan, Create – In a ‘vineyard terracing’ concert hall, the audience is sub-divided. This provides additional supporting reflections and also ensures that more of the audience can be seated close to the orchestra. Both help the orchestra to achieve a loud sound.
  • Improve – If necessary, reflectors and diffusers may be used to provide beneficial supporting sound reflections

That’s engineering

  • directivity of a sound source describes how effectively the sound is radiated in various different directions.

Engineering ideas

  • sound, waves, amplitude, frequency, loudness, auditory, acoustic, amplification, acoustics, pressure, vibration, oscillation, oscilloscope

Do It
Challenges for you to work on…

  • Changing sounds – do the experiments, then take the quiz
  • Music Acoustics – a beginner course for music, sound and physics. It shows how physics and music are related. Music and math have a great relationship and this simulation clearly described that.
  • Vibration and sound energy activities
  • Sound Uncovered (interactive simulation, app, free) – Explore the surprising side of sound, auditory illusions, acoustic phenomena, and other things that go bump, beep, boom, and vroom. Hear with your eyes, see with your ears, make and modify recordings, test your hearing, and more. How do you make a saxophone growl? Are there secret messages in music played backward? Can you talk and listen at the same time? Why does the sound of gum chewing drive some people mad?

Learn more…