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Cambridge Ultrasonics
Cambridge, UK
Consultancy service in physics, electronics, maths & ultrasonics

Cambridge Ultrasonics

Animal hearing range

Animals are different to humans in terms of hearing ability.

Some animals can hear frequencies between 0.03 Hz to 120 kHz.

Cambridge Ultrasonics' microphone system can detect sounds up to 120 kHz.

Our signal processing allows us to detect repetitive sounds that are fainter than the threshold of hearing.

Building Monitoring

Sound, infrasound and ultrasound can propagate through buildings. Infrasound is more commonly known as vibrations and covers the frequency range below 20 Hz. Ultrasound covers the frequency range above 20 kHz. The range from 20 Hz to 20 kHz is considered to be the range of human hearing, although increasing age generally results in poorer sensitivity to high frequencies. The range of human speech covers roughly 100 Hz to 10 kHz although above 1 kHz the range is associated with sybilant sounds such as "s" and "sh" or fricative sounds such as "f" and "t".

Young women are probably subconciously aware of frequencies between 20 kHz and 25 kHz - generally making them feel unwell or stressed.

Animals have different ranges of hearing from humans. Cats have a very wide range of frequencies they can hear, from: about 0.05 Hz to 70 kHz although they more commonly use frequencies between 0.3 Hz to 40 kHz. Mice can hear over the range 2 Hz to 80 kHz but generally use frequencies between 12 kHz to 20 kHz. Rats have  a hearing range of 0.5 Hz to 60 kHz and use frequencies of 5 kHz to 40 kHz..

Cambridge Ultrasonics has research grade equiment for detecting sounds over the range 20 Hz to 120 kHz. We can analyze the sounds to detect different frequency components (Fourier transformation) and this technique together with other signal rpocessing allows us to detect repetitive sounds that are well below the threshold of human hearing.

Possible sources of sound that may be problematic are: building work, pneumatic and percussive hammers used for breaking concrete and brickwork, movement of heavy vehicles, grinding, drilling, noise from ultrasonic cleaning equipment, dental drills, fans, doors opening and closing, steam generators, boilers and heating systems.

Buildings used for research and development (R&D) may have equipment or animals that are sensitive to sounds. In the case of equipment the sensitivity may extend up to very high frequencies of say 10 MHz or more. In this case we have the ability to source or design and build equipment to detect ultrasound at frequencies higher than 120 kHz. In the case of animals our microphone system should be sufficient.

In many materials, ultrasound is attenuated more raipdly than sound; in many materials, sound is attenuated more rapidly than infrasound. As a general rule ultrasound will propagate with greater attenuation than sound and infrasound. However, in metals the rate of attenuation of ultrasound is much lower can in, say, wood or brickwork or the air. However, ultrasound can propagate through 2 m of high strength concrete and still be detected. Pipes can form waveguides for ultrasound and sound helping them propagate through buildings. Water can allow ultrasound to travel through many metres so water filled pipes are a particular problem.

Monitoring of a building is the best way to establish if there is a potential problem.

Cambridge Ultrasonics is able to record signals from a source with ultrasonic components and then replay the sounds to discover if there will be a problem with a particular source if it is moved to a new location. We can also advise on mitigation methods. All this can be done before the expense is incurred in moving the source so that the eventual move is done with no repercussions and little or no expensive reworking.