How Do You Measure Sound Frequency?

Sound waves are waves of pressure that oscillate between stretching or compressing the medium they move through, which is in our case air, at a certain frequency.  The higher the frequency these waves oscillate at, the higher in pitch the sound is heard when the wave reaches the eardrum. Our brain’s perception of these pitches relies on how many of the compressions our ears can sense in a second. High-frequency sounds, such as a whistle being blown, oscillate at a high frequency and are heard as high pitch sounds by our ears. On the other hand, low-frequency sounds, such as plane taking off, oscillate at a low frequency and emit low-pitched sounds. The human hearing range is an impressive thing—we can hear both in intensity (loudness) and frequency (pitch). The ear is capable of hearing a lot, but surprisingly, it can’t hear everything. Sounds that are on the higher end of the frequency spectrum quickly fade from our hearing range. For example, dog whistles emit a sound at such a high frequency that human ears cannot hear it. Unfortunately, unlike a dog’s ears, our ears haven’t evolved to hear at such a high frequency. Although these sounds are often unthought-of, they are crucial to many processes and professions. Understanding pitch is a necessity to those in music, music engineering, acoustics, and psychoacoustics. So, how do you measure something that might not even be heard? Firstly, let’s understand the unit of measurement used: the Hertz.

The Unit of Measurement

The unit used to measure pitch is Hertz (Hz). Hertz is a measure of cycles per second. When sound waves oscillate, they change in pressure. A sound wave cycle consists of a sound wave reaching high pressure, dropping to low pressure, and then reaching high pressure again. The amount of time a sound wave does this in one second is measured, and this number is called the Hertz. Everyone knows the annoying high pitch sound of a mosquito, but did you know that mosquito is emitting a 400 Hz to create its flight tone? That’s 400 sound wave cycles in one second. Going back to the dog whistle, this emits between 16,000 and 22,000 Hz, which is just out of range for humans.

How are Hertz measured?

Scientists and engineers typically use oscilloscopes to measure frequency. An oscilloscope creates a graphical representation of a waveform. To measure the pitch of a sound, the sound is transmitted by audio cables or a microphone to the device. The oscillator then displays the sound on the screen in moving waves that are a visual representation of the sound. The user then adjusts the setting until the waveform is stationary. The adjustments they make indicate the Hertz of the sound.

Understanding frequency, pitch, and Hertz is critical to understanding how sound and our hearing works. With age, our hearing abilities often diminish, and this includes our sense of sound frequency. If you think your ears might not be picking up all of your surrounding sounds and frequencies, it’s a good idea to consult a professional.

Attune is an independent provider of hearing healthcare in Australia. Established with a formidable medical alliance, Attune provides high-quality services and shows a great understanding of hearing-related conditions. If you’re worried about your hearing, call today on 1300 736 702 to schedule an appointment with an expert.