What is Sound?

Explore how sound waves arise from material vibrations, and learn that frequency, measured in Hz, is the number of cycles per second that determines pitch.

Explore how sound waves relate frequency and wavelength, revealing that higher frequency yields shorter wavelengths. See examples: 200 Hz with 1.7 meters and 20,000 Hz with 17 centimeters.

Understand the phase relationship between waves, including in phase, out of phase, and phase inverted, measured in degrees, using sine waves and a 300 Hertz example in Cubase.

Learn to calculate sound frequency and wavelength from the speed of sound. Use f = v / lambda with v = 344 m/s; 17 m yields 20 Hz.

Decibel is the unit to measure sound intensity in dB on a logarithmic scale. It ranges from 0 dB to 120 dB, with doubling volume about 6 dB.

Explore how sound speed, measured in meters per second, varies with medium and temperature, and learn to estimate thunder distance using the speed of sound.

Explore how sound reflection occurs when a sound wave hits a surface and returns to its origin, shaping perception in different spaces and creating echo and reverb.

Hear how echoes arise from a reflected sound, distinguishable from the original. Surfaces at least 17 meters away produce echoes arriving 0.1 seconds later, while closer surfaces create reverb.

Explore how rapid reflections create reverb, with early and late reflections adding to an extended sound perceived as continuous by the brain.

Discover how sound absorption converts energy into heat, with complete or partial absorption by materials like carpets and curtains, shaping room acoustics and enabling studio simulations.

Explore the limits of human hearing by detailing the 20 Hz to 20,000 Hz range, age-related decline, and headphone frequency response tests revealing hearing limits.

Explore the human ear's range from 0 dB to 120 dB, the threshold for pain and damage, and why air traffic controllers wear hearing protection, shown in dB SPL.

Explore the nonlinearity of human hearing and its bias toward middle frequencies like speech, and how Fletcher and Munson curves show automatic compensation in car radios.

Tonality describes frequency and pitch of a sound, shown by notes from C to B and piano; higher scales raise frequency and pitch, lower scales lower them, A4 440 Hz.

Explore how the ears and brain turn sound waves into the sensation of hearing. External, middle, and inner ears highlight voice frequencies, localize sound, and convert vibrations into neural impulses.

Learn how the brain uses the time difference for sound arrival between the two ears to locate sounds in space, influenced by absorption and reflection at the ears.