Hello everyone! If we want to use an acoustic instrument to compare human ears, this acoustic instrument must be the "microphone".

After hearing the sound, the human's ear transmited the sound information to the neural network, which was analyzed and judged by the brain. Similarly, by picking up the sound, the microphone passed the sound signal to the data acquisition instrument and the analysis software to evaluate the acoustic signal. Therefore, choosing a suitable and accurate measurement microphone was to match a "healthy and comfortable" ear for the whole acoustic measurement system. Whether the microphone selection was appropriate or not was directly related to the accuracy of subsequent tests.

This issue gave a systematic introduction to the microphone, including its development history, main parameters, SKC noise measurement microphone, surfacemicrophone and probe microphone. We hoped it can help engineers in acoustic testing to choose a cost-effective measurement level microphone.

Development history of microphone

The history of microphone could be traced back to the end of the 19th century. Alexander Graham Bell and other scientists were committed to finding a better way to pick up sound for improving the latest invention at that time - telephone. During this period, they invented liquid sensor and carbon particle sensor. The effect of these sensors was not ideal and only be used reluctantly.

In 1949, winniburst Laboratory (the predecessor of Sennheiser) developed MD4 microphone, which could effectively suppress sound feedback and reduce background noise in noisy environment. This was the world's first noise reduction sensor that suppresses feedback.

In 1961, Sennheiser introduced mk102 and mk103 sensors at the Industrial Expo in Hanover, Germany. These two sensors interpret a new sensor manufacturing

concept - RF capacitive type, that is, small and thin diaphragm was adopted. The diaphragm had the characteristics of small volume, heavy halo and light halo, and could ensure excellent sound quality. Their impact on climate had strong anti-interference performance and was suitable for some new fields.

In the 20th century, microphones developed from resistance conversion to inductive and capacitive conversion. A large number of new microphone technologies had gradually developed, including microphones such as aluminum strip and moving coil, as well as capacitor microphones and electret microphones widely used at present.

Main parameters of microphone

1. Sensitivity

Sensitivity was an index characterizing the acousto-electric conversion ability of microphone, was the output voltage or electric power under the action of unit sound pressure, was the ratio of output voltage at the output end of microphone to sound pressure at the input end, and its unit was MV / PA.

2. Frequency response

Frequency response referred to the relationship between microphone output level and frequency, which was usually expressed by the nonuniformity within a given frequency range or the effective frequency range within a certain nonuniformity.Generally speaking, the better the frequency response of the microphone, the better the performance. The characteristic curve of microphone sensitivity varying with frequency was the frequency response curve.

3. Dynamic range

The dynamic range referred to the whole range from the lowest sound pressure to the highest sound pressure that could be measured by the microphone. This was not only the unique characteristic of the microphone, but also the preamplifier used with the microphone had its own dynamic range / the dynamic range of the microphone depends on its sensitivity to a great extent.

4. Maximum sound pressure level

When the harmonic distortion of the microphone reached a certain allowable value, the sound pressure level was the maximum sound pressure level of the microphone. The maximum sound pressure level reflected the upper limit of microphone operation.

SKC measurement microphone

As the foundation of SKC, noise sensor had accumulated nearly 10 years of production and sales. The product had stable performance and high production process level. At present, domestic customers included major universities, scientific research institutes and social enterprises. The international customers also spread all over Europe, America and other countries in Asia at the same time.

The measurement microphone produced by SKC was between 1 inch and 1/4 inch, which could meet the requirements of various occasions. For most application scenarios, the type of sound field during application should be considered first. Microphones could be roughly divided into free field and pressure field according to the type of sound field. For the indoor environment far away from the reflecting surface or with good sound absorption performance, such as outdoor test with sound level meter or a large number of sound damping materials in the room, the free field measurement microphone was the best choice. For the test in a closed coupling cavity or close to a rigid reflecting surface, the pressure field microphone was more suitable. The following figure was a list of parameters of free field microphone and pressure field microphone.

Production inspection of SKC measurement microphone

Each noise sensor of SKC had undergone strict experimental test, and could be delivered only after passing the test. In addition to conventional sensors, SKC had microphones for special purpose testing. Such as surface microphone and probe microphone. Specific parameters and uses were as follows:

SKC surface microphone

Confined space embedding test, clay model embedding test, ground array measurement, wind tunnel application test, general noise measurement.

Typical application and application of probe microphone——SKC probe microphone

Acoustic impedance measurement, exhaust system measurement, near-field measurement, high temperature measurement, pressure distribution measurement in small sealed chamber.

We have introduced so many kinds of microphones for you. You can choose the appropriate microphone according to the test needs, or you can contact our technicians at any time to select the type for you. We hope you can pick up the most "real" sound in the acoustic test!