Sound
On this page
Our ears are an amazing site of many sensory systems, including how we hear.
How and what we hear is due to the incredible set of percussive biological features of our ‘auditory’ system, and how our brain interprets these vibrations.
While we can assume that sound ‘speaks for itself’, there are many people who cannot access this sense and what it has to offer.
This requires us to think of different ways we can share sound – including the interpretive skills of audio description, sign language and written explanations. Having both the language and additional formats to explain the audible qualities of collections benefits everyone.
Exploring and recording sounds can provide greater access to collections, support conservation of pieces that are too fragile to be used, and find the potential of items that may not usually be considered for their audible qualities.
Follow on to learn more about the benefits of sound to your collections information and interpretation.
Let’s hear a little more about sound
Watch the video and/or read the transcript below.
Transcript
You hear the gentle lap of waves, the distant cawing of a seagull. But then an annoying whine interrupts the peace, getting closer, and closer, and closer. Until…whack! You dispatch the offending mosquito, and calm is restored.
How did you detect that noise from afar and target its maker with such precision?
The ability to recognise sounds and identify their location is possible thanks to the auditory system. That’s comprised of two main parts:
- the ear
- the brain
The ear’s task is to convert sound energy into neural signals; the brain’s is to receive and process the information those signals contain.
To understand how that works, we can follow a sound on its journey into the ear.
- The source of a sound creates vibrations that travel as waves of pressure through particles in air, liquids, or solids.
- But our inner ear, called the cochlea, is actually filled with saltwater-like fluids.
So, the first problem to solve is how to convert those sound waves, wherever they’re coming from, into waves in the fluid.
- The solution is the eardrum, or tympanic membrane, and the tiny bones of the middle ear.
- Those convert the large movements of the eardrum into pressure waves in the fluid of the cochlea.
- When sound enters the ear canal, it hits the eardrum and makes it vibrate like the head of a drum.
- The vibrating eardrum jerks a bone called the hammer, which hits the anvil and moves the third bone called the stapes.
- Its motion pushes the fluid within the long chambers of the cochlea.
- Once there, the sound vibrations have finally been converted into vibrations of a fluid, and they travel like a wave from one end of the cochlea to the other.
- A surface called the basilar membrane runs the length of the cochlea.
- It’s lined with hair cells that have specialised components called stereocilia, which move with the vibrations of the cochlear fluid and the basilar membrane.
- This movement triggers a signal that travels through the hair cell, into the auditory nerve, then onward to the brain, which interprets it as a specific sound.
When a sound makes the basilar membrane vibrate, not every hair cell moves – only selected ones, depending on the frequency of the sound. This comes down to some fine engineering.
- At one end, the basilar membrane is stiff, vibrating only in response to short wavelength, high-frequency sounds.
- The other is more flexible, vibrating only in the presence of longer wavelength, low-frequency sounds.
- So, the noises made by the seagull and mosquito vibrate different locations on the basilar membrane, like playing different keys on a piano.
But that’s not all that’s going on. The brain still has another important task to fulfil: identifying where a sound is coming from.
- For that, it compares the sounds coming into the two ears to locate the source in space.
- A sound from directly in front of you will reach both your ears at the same time.
- You’ll also hear it at the same intensity in each ear.
- However, a low-frequency sound coming from one side will reach the near ear microseconds before the far one.
- And high-frequency sounds will sound more intense to the near ear because they’re blocked from the far ear by your head.
- These strands of information reach special parts of the brainstem that analyse time and intensity differences between your ears. They send the results of their analysis up to the auditory cortex.
- Now, the brain has all the information it needs:
- the patterns of activity that tell us what the sound is
- and information about where it is in space
Not everyone has normal hearing.
- Hearing loss is the third most common chronic disease in the world.
- Exposure to loud noises and some drugs can kill hair cells, preventing signals from travelling from the ear to the brain.
- Diseases like osteosclerosis freeze the tiny bones in the ear so they no longer vibrate.
- And with tinnitus, the brain does strange things to make us think there’s a sound when there isn’t one.
But when it does work, our hearing is an incredible, elegant system. Our ears enclose a fine-tuned piece of biological machinery that converts the cacophony of vibrations in the air around us into precisely tuned electrical impulses that distinguish claps, taps, sighs, and flies.
There are a multitude of ways we can describe sound
Taking terminology from the world of music, here are some categories you should consider.
| Category | Description |
|---|---|
| Direction | What direction the sound is coming to/from, in what direction you can hear it. |
| Duration | The length (in time) of the sound. |
| Dynamics | How loud or quiet the sound is (either the overall sound or individual parts of it). |
| Harmony | The relationship between two or more simultaneous sounds. |
| Pitch | How high (think Mariah Carrie high notes) or low (think Paul Robeson’s Ol’ Man River) it sounds. |
| Pulse | Whether there is a rhythmic ‘beat’ to the sound. |
| Rhythm | The pattern of regular or irregular pulses of the sound, and whether they are strong or weak pulses. |
| Source | Where the sound is coming from. |
| Structure | How the sound is structured (does it have ‘sections’). |
| Tempo | The speed of the pulses of a sound. |
| Texture | The way different sounds are combined to make one sound/soundscape. |
| Timbre | The quality or character of a sound (e.g. does it feel big like a bassoon deep sound, or small and light like a flute’s soft tune). |
| Tonality | (Similar to vision) what is the overall tone of a sound that can affect the ‘mood’. |
Need some specific terminology?
Check out Amanda Patterson ‘106 Ways To Describe Sounds’ on Writers Write for some specific words you could use to describe sounds: www.writerswrite.co.za/106-ways-to-describe-sounds/
The most effective way to understand and describe sound is by testing it out.
Choose 2 items:
- Something that you have to interact with to make sound (a drum, clicking a pen)
- Something that makes sound by itself (the rain, a kettle boiling) – you may want to use something like this ‘Forest Birdsong’ video on YouTube to try this out:
Remove any other audible distractions (where possible) so you can concentrate on the sound. Focus on each aspect of the sound (where there are multiple layers) and then all at the same time. Try answering these questions.
- What is the source of the sound?
- What direction are you hearing it from?
- How quiet/loud is it?
- What pitch is it?
- Does it have a rhythmic pulse? If so, what is it like?
- How long does the sound last?
- What is the ‘character‘ of the sound? (think timbre and tone)
- What changes if you move closer or further away from the source of the sound?
- Is it pleasant or unpleasant? Why?
- How does it make you feel? (e.g. happy, uneasy, scared, bored)
Want some TSM content to help you out?
For an example of describing a sound, check out Sophie’s Sound of Comfort on our TSM podcast
For a different angle, check out this video on becoming a better listener.
You may find this useful for working with any audio visual content, as well as to develop your emotional literacy and skills.
Want to know more about Tinnitus?
This Ted-Ed video provides information on this phenomenon that is a part of many of our auditory systems.