What Is A Sound vs. An Echo? Echolocation Basics
- Taylor Cook
- Dec 21, 2025
- 8 min read
A deceptively simple question. This article explores basic elements of echoes and options of technique or perception available to an echolocator. There are other better informed sites if you wish to learn more from a physics basis.
Defining
In this article, “sound” and “echo” are described primarily from a perceptual and cognitive perspective rather than a strict physics definition. This reflects how echolocators experience and use acoustic information in real-world situations. So, what is a Sound and what is an Echo from an echolocators perspective?
A Sound: Acoustic information being created in the environment (ex. Loudspeaker creates sound in air)
An Echo: Acoustic information that has been transformed after encountering a surface of a different medium. (ex. Sound interacted with a material, creating an echo)
What is Active And Passive Echolocation?
Active echolocation is defined as an intentional single sound to create an echo for the listener.
Passive echolocation is defined as an incidental-appearing single sound to create an echo that others may not be aware of its use.
While these are traditionally established descriptions of the sound used, for this project I have created a more comprehensive objective breakdown of sounds used.
While these traditional terms are useful, they don’t fully capture how echolocators actually choose, control, and perceive sounds in practice. For that reason, the rest of this article uses a more function-based breakdown of sound types.
What Makes A Sound, A “Sound” In Echolocation?
It's an “intentional” sound. An unexpected sound makes an unexpected echo and isn't useful for an echolocator
It's a “distinct” sound relative to the echolocators perspective.
It's usually a sound made by the person, but does not have to be generated in the echolocators immediate reach. For simplicity, it is most efficient to choose a sound consistently made in the students' immediate vicinity.
Usually sounds are described with traditionally used terms to describe the skill overall for example “active” or “passive” echolocation. But both of these create an intentional and distinct sound and echo from the listeners perspective.
What Kind Of “Intentional” And “Distinct” Sounds Are Available For An Echolocator To Use?
Single Sound (ex. Click, Clap, Tap) - Most people only need a single echo to learn enough information to make a decision. This is the simplest kind of sound most people can process at an entrance or beginner level. A common technique that focuses of using single sounds is the established FlashSonar which he will refer to as the “traditional technique” or “commonly recognised technique”.
Multiple Single Sounds (ex. Repetitive Single Sound) - Some people cognitively compare echo “snapshots” made in quick succession before making a decision, when not enough information can be found in a single echo. I call the applying of this approach “double takes”
Resonance/White-noise Constant Sound - (ex. Bell, White Noise, Constant Tone) A constant sound, makes a constant echo and behaves differently than other simpler sounds in how we perceive them. This is further explored in the future article Complex Sound application
Variable Sounds - (ex. Music) This is the most complex kind of sound to make, and makes an equally complex echo. This is further explored in the future article Complex Sound application
In practice, most effective beginner sounds fall into a “middle zone”: quick, controllable, socially acceptable, and within the frequency range of human speech.
How Do You Choose A Sound To Use?
Most people choose a single sound to begin with, it's the simplest kind of echo to process and understand.
a majority of people choose a single or multiple-sound approach and its ease of use is mostly influenced by personal preferences of the student.
Those previously mentioned common examples tend to have something in common to being called here people would think of as the sweet spot.
Sounds that are too loud or too high frequency are socially awkward and can disturb the people around you greatly. While choosing a quiet or too low frequency sound, the echo is lost to silence amongst other competing sounds in the environment.
There is a middle range in human hearing. Not too loud, not too quiet. Not too low or too high pitch and that range falls in the middle of the typical human speech range of sounds (which explains why tongue clicks are one of the most popular sounds to use).
For beginners, it's best to choose a quick sound. This gives the biggest time delay between sound stopped and echo began from the listeners perspective. This extra gap helps the listener learn about the “time delay and distance” relationship and information.
You shouldn't pick a sound that's too quiet because the quieter echo returns quieter beyond the human range of hearing. While a sound that's too loud is socially uncomfortable for most users.
You shouldn't pick a sound that's too high or low frequency also. Shorter wavelengths lose energy faster through the air than longer wavelengths, but provide more “fine grain” information for the listener. So there is a middle ground compromise between the two that works for any expected distances being used around echolocators.
You should not feel pressured to use a particular sound regardless of popular strategies. Sometimes you need to tweak your approach for the environment or as you learn more. It should be a sound you feel comfortable producing and controlling.
Tongue clicks are a common choice of sound chosen. Not only is it quick and sharp, making an equally quick and sharp echo. But the shape of the mouth can make it highly efficient at being directional. You can move your head and change the direction of the sound to improve or lessen the echo response.
Another popular sound choice is a hand clap or flinger click. This is popular for also being quick and sharp, making for an efficient echo to perceive. However unlike tongue clicks it is not directional. Changing any of the three distances; between the listener's head, the source of sound and the surface reflection all change the strength of echo response.
For years, the sound I primarily used was the “thud” sound from my heel when walking, supplying a constant repetition of echoes for my whole day. It was socially unobtrusive, but also my heel strike while walking was a bit louder than most peoples. This worked for me and how I used it and you too can be as creative as you want or stick with what's popular.
Making An Echo: Basic Echolocation
Basics: Directional Echoes: Focus On A Straight line
First we're going to explore how to understand directional echoes in your environment by going through the components of echolocation and explaining the above diagram.
We are going to begin with some simple demonstrations. Let's treat echoes bouncing off a surface the same way a ball bounces off the ground. This situation would be illustrated like the previously shown basic echolocation mechanics diagram.
Let's focus on how the arrowed lines “bounce” off the surface and change direction, in the diagram they are called sound and echo in the same way as the prior description.
When you make a sound, it will travel outwards, towards the surface you want to sense with echolocation. It will hit the surface and bounce off the same way as light bounces off a mirror.
If you make a sound close to your face, the sound will efficiently bounce back towards your face. If you make a sound lower on your body, like a low hand clap or tap of a cane on the ground. The echo will bounce off the wall lower to the ground before travelling towards the listener.
While this sounds simple, it's an important principle to learn the relationship of the height of the loudest echo from off the ground to help you sense objects that you can choose how close the echo bounces off a surface above the ground level.
If the surface your sensing is now angled away from you like illustrated below. The energy in the echo now bounces off and away from you. You would not hear the echo coming back like before.
If there's a gap in a surface, like a doorway, there's an audible gap in the echo you receive.
If you learn and practice to understand how echoes change based on their shape and where you stand near them. You can learn to sense these differences and learn if you have heard enough echo to sense the surface in question.
Intermediate: Non Directional Echoes: Bubbles Propagating Outward
Let's explore non-directional echoes. Visually this would appear like a bubble, with the surface that the sound bounced off being in the center of that bubble.
Unless you are using advanced metamaterial speakers, sounds created are governed by wave theory. This means, while sound can have a singular direction for some of its energy, the rest travels out as a bubble, travelling out in every direction from a sound source. Bouncing off some surfaces back to the listener, while some bounce away from the listener and not heard.
This “bubble” effect of sound dispersing into the environment creates some interesting potential. Ability to listen to sounds from around corners and apply echolocation to that auditory information. You can use this effect to effectively learn to mentally see around a corner unlike eyesight. (While this doesn’t allow precise object identification around corners, it can provide useful spatial cues about openness, boundaries, and movement)
Energy in a sound and in an echo obeys the square law rule, there in simple terms means more energy and information is lost the longer it travels before it's final destination. This is a useful beginner point in understanding distance information since echoes are quieter the further they travel, as well as the echoes time delay helps confirm the distance information for the listener.
Kinds of Echoes
There are three kinds of echo phenomena that an echolocator can perceive and tell their information apart. Here is a detailed description of the different kinds with a diagram afterwards demonstrating their nature within the echolocators environment.
Reflected Echo, this is the echo that bounces off a surface. It's the strongest echo, contains the most information and most commonly used source of information in echolocators.
Absorbed Echo, this is an echo that changes as it travels through a second medium/material than the sound was. An absorbed echo doesn’t disappear; instead, the sound energy is transformed inside the material, often changing how and whether it later re-emerges. Perceiving an absorbed Echo is more difficult, less sound information is absorbed than reflected in most typical situations.
Emitted Echo, some materials resonate their absorbed Echo and re-emit their own echo into the environment. A real world example is how bells are “ringing”.
Let me follow you through the steps illustrated in the diagram above how all three can work sequentially and together in unison. Let's explore the example of striking a bell:
When a bell is struck, a sound is created at the moment of impact. This initial acoustic impulse travels through the air toward the bell and outward into the surrounding space. This is the source sound generated by the strike.
As the sound wave meets the surface of the bell, part of its energy is immediately reflected back into the air. This reflected energy forms a distinct, early echo that can reach the listener directly, carrying information about the surface and shape of the bell. This is the reflected echo.
At the same time, some of the sound energy enters the material of the bell itself, where it is transformed into internal vibrations. This energy is no longer moving through air but through the bell’s structure, temporarily stored as mechanical resonance. This stage is the absorbed echo.
As the bell continues to vibrate, that stored energy is gradually released back into the air as sustained sound. This re-emission produces the familiar ringing of the bell, which carries transformed acoustic information over time. This is the emitted echo.
Echolocation begins not with complexity, but with understanding how sound changes as it moves through the world. By learning to distinguish between source sounds, reflected echoes, absorbed vibrations, and re-emitted sound, echolocators gain a clearer sensory framework for interpreting their environment. These distinctions help transform vague acoustic impressions into meaningful spatial information and provide a foundation for more advanced practice. With attention and repetition, what initially feels abstract becomes intuitive, allowing echolocation to function as a reliable, adaptable skill rooted in everyday interactions between sound, space, and material.
Comments