Sound frequency
Sound (or audio) frequency is the speed of the sound’s vibration which determines the pitch of the sound. Sound is caused by vibrations that transmit through a medium such as air and reach the ear or some other form of detecting device.
It is measured as the number of wave cycles that occur in one second, with the standard unit of measurement being Hertz (Hz)
Sound intensity is measured in Decibels (dB). This is a logarithmic scale in which an increase of 10 dB gives an apparent doubling of loudness.
A frequency of 1 Hz refers to one wave cycle per second, while 20 Hz refers to 20 per second, where the cycles are 20 times shorter and closer together.
The audio spectrum is the frequency range that is audible to humans. This generally spans from 20 to 20,000 Hz, although environmental factors influence the precise range for each individual.
Frequencies at the high end of the spectrum are the first to be negatively affected by age and/or hearing damage as a result of prolonged exposure to loud volumes or noise.
As well as intensity and frequency, sound also transmits information. For example, music or speech, transmit the information which people may perceive differently from other sounds.
Approved document E, Resistance to the passage of sound defines ‘frequency’ as:
The number of pressure variations (or cycles) per second that gives a sound its distinctive tone. The unit of frequency is the Hertz (Hz (formerly called ‘cycles per second’).
A ‘frequency band’ is a continuous range of frequencies between stated upper and lower limits. An ‘octave band’ is a frequency band in which the upper limit of the band is twice the frequency of the lower limit. A ‘one-third octave band’ is a frequency band in which the upper limit of the band is 2 times the frequency of the lower limit.
The sound-absorbing characteristics of materials vary significantly with frequency. Low-frequency sounds, below 500 Hz, tend to be more difficult to absorb whereas high frequencies sounds, above 500 Hz, are easier to absorb. A material's sound absorbing properties can be expressed by the sound absorption coefficient, alpha, as a function of frequency, where alpha ranges from 0 (total reflection) to 1.00 (total absorption).
Similarly, the sound insulation of materials varies with frequency. Low-frequency sounds tend to be attenuated less by passing through sound insulating materials than high-frequency sounds. As a result, the sound attenuation properties of materials are generally measured at a range of frequencies representative of normal human hearing and this is then compared to a reference frequency profile such as that defined in BS EN ISO 717-1 Acoustics. Rating of sound insulation in buildings and of building elements. Airborne sound insulation.
[edit] Related articles on Designing Buildings Wiki
- Acoustic consultant.
- Airborne sound.
- Approved Document E.
- Building acoustics
- Building Bulletin 93: acoustic design of schools.
- Building regulations.
- Flanking sound.
- Impact sound.
- Noise nuisance.
- Reverberation.
- Robust details certification scheme.
- Room acoustics.
- Sound absorption.
- Sound insulation.
- Sound power level.
- Sound reduction index (SRI).
- Sound v noise.
- Structure-borne sound.
Featured articles and news
A sun, tide, mass or scratch dial.
A brief description of time in the sun.
ICE Trustee Board update June 2022
Given by ICE President Ed McCann.
Artificial intelligence and project management
Two new research reports published by APM.
Association for Project Management membership offer
50% off APM Associate membership for Designing Buildings users.
Building safety, a shifting landscape for professionals
A commentary from the insurance perspective.
In brief with further links.
Walter Segal: self-built architect
A definitive book on a pioneer of green architecture.
Funding for heritage on the high street
Using heritage as a catalyst for reviving historic centres.
Commonwealth Heads of Government Meeting update.
Declaration prioritising sustainable urbanisation adopted.
A small hidden, often distant but key building component.
Some brief words about the actuator.
CIAT Chief Executive steps down.
After 34 years at the Institute.
Volunteer opportunity launched by the ICE
To support the next generation of engineers.
Provisional findings show illegal cartels in the industry.
CIAT reporting from the Competition and Markets Authority.
Making sustainable construction number one priority.
The future of construction report.
Interview with ECA CEO.
Many provisions came into force on June 28, 2022.
With room to expand.
An information packed session at the BSRIA conference.
Refurbishment, Energy Efficiency, Indoor air and process.
Create a profile, write informed product articles and share.
Aluminium Composite Panels (ACP) is one example.
We are indeed now 10 years old, so go on and be bold !
Write about something you know, help us build and grow !