1) Why is frequency an element needed in the sound industry?
and
2) When there is a sound pressure level of two different sources with different frequencies, why do sound pressure levels have to be determined in each separate frequency?
1) The sound industry sells equipment that produces, attenuates or amplifies sound. Acoustic design of auditoriums is a part of the industry. The performance depends upon the frequency (pitch) of the sound. The audible frequency range of 20-20,000 Hz is most important.
2) When there is more than one frequency present, the sound pressure does not vary as a simple sine wave, and the sound pressure levels of the separate frequency sounds are not additive. Sound intensity (power/area) is proportional to the square of the sound pressure level, for each frequency.
To get the answer to the first question, why frequency is important in the sound industry, we can start by understanding what frequency represents in the context of sound. Frequency refers to the number of complete cycles of vibration per second, and it is measured in Hertz (Hz). In the case of sound, frequency determines the pitch of the sound.
In the sound industry, frequency is an element that is needed for various reasons:
1. Equipment Design: Different audio equipment, such as speakers and microphones, are designed and optimized to work effectively within specific frequency ranges. For example, a subwoofer is designed to reproduce low-frequency sounds, while tweeters are designed for high-frequency sounds. Understanding the frequency characteristics allows engineers to design equipment that accurately reproduces or captures sound within the desired frequency range.
2. Sound Mixing and Production: In music production and sound mixing, different instruments and vocal tracks occupy different frequency ranges. By understanding the frequency content of each sound source, audio engineers can adjust the levels, equalization, and other settings to create a balanced and cohesive mix. This also helps in creating space and clarity within the audio mix.
3. Acoustic Design: In the design of concert halls, recording studios, cinemas, and other acoustic spaces, frequency is a crucial factor. The characteristics of room acoustics, such as reverberation and resonance, are frequency-dependent. By considering the frequency response of the room, engineers can optimize the acoustic properties to provide a balanced and immersive listening experience.
As for the second question, why sound pressure levels need to be determined for each separate frequency, we need to understand the behavior of sound waves. When sound waves of different frequencies coexist, the resulting sound pressure is not simply the sum of the individual sound pressures.
Sound pressure levels are determined based on the amplitude of the sound wave, which is a measure of its intensity. However, sound intensity is not directly additive for different frequencies. This is because the phase relationships between different frequencies can result in constructive or destructive interference, leading to variations in the overall sound pressure levels.
Therefore, to accurately measure and understand the sound pressure levels when multiple frequencies are present, it is necessary to measure them separately for each frequency of interest. This allows for a more precise analysis and evaluation of the sound characteristics at different frequencies, which is important in various applications, including audio engineering, room acoustics, and noise control.