Download PDF – Sound: Reverberation, and Range of Hearing

REVERBERATION :

It is the persistence of a sound after a sound is produced.

A reverberation is created when a sound signal is reflected multiple of times until it reaches a sound wave that can not be heard by human ears.

It usually takes place in a big hall or auditorium.

Excessively reverberation is highly undesirable due to which the roofs and walls of the auditorium are generally covered with sound-absorbing material like compressed fireboards, rough plaster for draperies.

The material of the seats is also selected on the basis of their sound-absorbing property.

Advantages of Multiple Reflection of Sound :

Horns, megaphones, loudhailers, musical instruments like trumpets, and Shehanais all are designed to send sound in a particular direction without spreading it in all directions.

It helps listeners and audience to listen to the speaker. 

This all could become possible just because of Multiple Reflection of Sound. 

Medical instrument “stethoscope” which is used for the listening sound produced within the body and specially used for heart and lungs, works on the same phenomenon that is multiple reflections of sound.

The ceiling of conference halls, cinema halls, concert halls are made curved so that sound after reflection can and even curved soundboard may be placed behind the stage so that sound after reflection can reach all corners of the hall and can spread evenly across the width of the hall.

Range of Hearing :

The audible range of sound for human beings is between 20 Hz to 20000 Hz (one Hz = one cycle/s)

The children under the age of five and some animals, such as dogs can hear up to 25 kHz (1 kHz = 1000 Hz)

As people grow older their ears become less sensitive to higher frequencies.

On the basis of the range of frequencies of a sound, it has been categorized as “infrasonic sound” or “infrasound” and “ultrasonic sound” or “ultrasound”.