The Basics of Sound Amplification

There are two types of hearing aids. One amplifies sound much like a regular pair of drugstore reading glasses. It has features like low and high amplification, noise reduction, and volume levels. Some models have multiple settings for different listening environments, including a telecoil. These aids can also be customized to fit the needs of a particular user. However, it is important to note that these devices are not for every person.

In the inner ear

The inner ear is a fluid-filled tube divided by hair cells that are covered with a thin elastic membrane. These cells are involved in sound amplification by converting pressure waves into electrical signals. The outer hair cells, meanwhile, act as mechanical amplifiers. They vibrate at the same frequency as the pressure wave and boost it as it passes. The result is an amplification of at least 10 times the original sound.

The cochlea is a cellular amplifier that can amplify a weak sound 100 to 1,000 times. These amplification abilities provide our auditory system with exceptional sensitivity and excellent frequency selectivity. The inner hair cells transform a mechanical signal into an electrical signal and the outer hair cells amplify the mechanical vibration of the cochlea’s basilar membrane. The outer hair cells can contract and elongate in response to a 70 kHz membrane potential oscillation. This process is called electromotility.

In the horn

The horn is an audio device with an exponential cross-section. The narrow end of the horn is called the throat, and the wider end is called the mouth. The transducer is placed at the throat, and pressure increases as the diaphragm moves near the horn. The pressure wave travels towards the mouth, where it increases in amplitude. This characteristic of a horn allows it to produce higher SPLs before distortion. Its speed and transient response are also superior to conventional drivers.

The horn’s narrow cross-sectional area makes it a highly effective loudspeaker. Because the sound is concentrated in one direction, it is louder and more easily heard by the listener. Horns are commonly used by the police to communicate with the public. Because of their efficiency in sound amplification, they are still used in modern technology. Here’s a closer look at how they work.

In the basilar membrane

Sound amplification through the basilar membrane occurs through the transmission of sound waves. Different frequencies reach their maximum amplitudes at various locations within the membrane, from one end of the basilar membrane to the other. The cochlea acts as a frequency analyzer, interpreting the sound as pitch at a location where the vibration is the largest. As the sound level increases, the magnitude of the peak frequency decreases. Then, as the sound level increases, the phase decreases again.

The height of the vibration of the basilar membrane determines loudness. The higher the sound, the more hair cells are stimulated and nerve impulses are generated. This phenomenon is called the cochlear volume displacement. In this study, researchers found that the cochlear volume displacement was ten times greater than the stapes vibration at ten dB SPL. As the sound level increased, the ratio of basilar membrane to stapes vibration decreased until it reached unity at 80 dB SPL.

In undercover police work

Undercover police officers have varying personality traits and are prone to problem outcomes. While many agents enter this corrupting environment with various character assets and flaws, those who exhibit poor impulse control, neuroticism, and desire for an unfamiliar experience are more likely to experience negative outcomes. Sound amplification can mitigate this problem by allowing officers to hear the surroundings in which they work, while still keeping their identities and locations private.

When conducting undercover investigations, audio amplification systems can be used to hear conversations in complete silence. These devices can be pointed at sounds to amplify them up to 10 times. This can help police officers catch individuals who are engaging in criminal activity without being detected. It is also useful in detecting those who are illegally accessing certain systems. Undercover officers need to be able to hear the surroundings, including their surroundings, in order to be successful.

In a cup

If you want to experiment with the properties of an in-a-cup sound amplification device, you can try to make your own. Using two disposable cups, you can funnel sound waves through the cup. Then, you can insert a cardboard tube into the holes and point it towards the openings. In this way, you can create a sound-amplification device in just a few minutes.

The acoustically reflective properties of the cups provide directional selectivity. Sound waves emitted by objects directly in front of the wearer will only be reflected through the cup’s inner surface, which focuses sound waves into the user’s ear canals. Likewise, if you turn the pinna of your ear forward, the waves are amplified and focused more precisely in the cup’s inner surface.