Measuring microphone capsules

Measurement microphone capsules are special microphone capsules that are used to measure sound. They are often used in audio technology, acoustics and measurement technology.

Measuring microphone capsules are designed in such a way that they can precisely record the sound pressure and convert it into electrical signals. They are characterized by high linearity, a wide frequency range and low distortion. This enables them to carry out accurate and reliable measurements of sound events.

Measurement microphone capsules are used, for example, for carrying out sound level measurements, calibrating audio devices, investigating room acoustics or analyzing sound events in the environment. They are also used in product development, quality control and research, where precise recording of sound signals is required.

There are various types of measurement microphone capsules, which differ mainly in their design and area of application. Here are some of the most common types:

1. Omnidirectional microphone capsule: This capsule has an omnidirectional characteristic, i.e. it picks up sound evenly from all directions. It is well suited for general measurements and outdoor recordings.

2. Cardioid microphone capsule: This capsule has a kidney-shaped characteristic, which means that it picks up sound best from the front and suppresses sound from the sides and rear. It is useful for reducing background noise and enabling better focusing on the sound source.

3. Eight-microphone capsule: This capsule has an eight-shaped characteristic, i.e. it picks up sound equally from the front and rear and suppresses sound from the sides. It is well suited for stereo recordings or for measuring sound sources that are located on both sides of the microphone.

4. Omnidirectional/cardioid/eight microphone capsule: This capsule makes it possible to choose between different characteristics by adjusting the directionality of the microphone. This offers more flexibility when recording or measuring sound in different environments.

There are also specialized microphone capsules such as pressure microphones for measuring sound pressure or microphone capsules with frequency response correction for more precise recording of certain frequency ranges. The choice of microphone capsule depends on the specific requirements of the application.

Measurement microphone capsules are special microphone capsules that are used for the precise measurement of sound. They consist of a combination of microphone elements and acoustic filters to correctly record the sound pressure level and frequency response.

The functionality of a measuring microphone capsule is based on the piezoelectric effect. Inside the capsule is a piezoelectric element that generates an electrical voltage under pressure. When sound waves hit the capsule, they generate pressure changes that deform the piezoelectric element and generate an electrical charge. This charge is then amplified and converted into an electrical signal that can be recorded by a measuring device.

Calibrating measurement microphone capsules is an important step to ensure that they provide accurate and reliable measurements. Calibration is normally carried out in special acoustic laboratories that have high-precision measuring equipment and procedures.

During calibration, the microphone is subjected to a reference sound pressure level that is precisely known. This sound pressure level is generated using reference microphones and sound sources that are also calibrated. The output signal of the microphone to be calibrated is then compared with the output signal of the reference microphone in order to detect any deviations.

Calibration also includes checking the frequency response of the microphone to ensure that it responds linearly over the entire frequency range. For this purpose, the microphone is exposed to sounds of different frequencies and the measured response is compared with a reference curve.

After calibration, the microphone capsule receives a calibration file containing the specific characteristics of the microphone. This file can then be used in measuring devices to correct the measurements and achieve more precise results.

When selecting a measurement microphone capsule, various attributes are important, which can vary depending on the application. Here are some important attributes:

1. Frequency response: The frequency response indicates how well the microphone is able to reproduce different frequencies. The more linear the frequency response, the more accurate and true-to-life the measured signals are reproduced.

2. Sensitivity: The sensitivity describes how well the microphone can detect weak sound sources. A higher sensitivity leads to better detection of quiet noises.

3. Directional characteristic: The directional characteristic indicates the direction from which the microphone picks up the sound best. Depending on the application, different directional characteristics may be required, such as omnidirectional, cardioid, figure-of-eight or supercardioid.

4. Noise level: The noise level or self-noise of the microphone is the noise generated by the microphone itself. Low inherent noise is important to ensure good signal quality.

5. Robustness and durability: Depending on the application, it may be important that the microphone capsule is robust and durable in order to withstand the demands.

6. Compatibility: The microphone capsule should be compatible with the corresponding connections and devices to ensure smooth integration and use.

These attributes are just a few examples, and the selection of a measurement microphone capsule ultimately depends on the specific requirements and intended use. It is advisable to obtain detailed information about the various options available before making a purchase and to seek professional advice if necessary.

Measurement microphone capsules are used in various areas of industry, particularly in acoustics and quality assurance. Here are some application examples:

1. Sound level measurement: Measurement microphone capsules are used to measure the sound level in different environments. This can be important in industry to monitor noise exposure for employees or to ensure that certain noise levels are maintained.

2. Acoustic investigations: Measurement microphone capsules are also used in acoustic tests, for example to analyze the sound of a product or to investigate the sound radiation of machines. This can help to make design improvements or ensure that a product meets the required acoustic standards.

3. Quality assurance: Measurement microphone capsules are used in quality assurance to ensure that products meet certain sound standards. For example, they can be used to check the sound quality of loudspeakers or headphones to ensure that they meet the requirements.

4. Vibration analysis: Measurement microphone capsules can also be used to measure vibrations, for example to analyze vibrations in machines or structures. This can help to identify potential problems or irregularities at an early stage and take appropriate action.

Overall, measurement microphone capsules enable precise measurements of sound levels, sounds and vibrations in industry in order to improve the quality of products, comply with safety standards and detect potential problems at an early stage.

The accuracy and precision of measurement microphone capsules are usually measured and evaluated using various parameters. These include:

1. Frequency response: The frequency response shows the deviations of the measured values as a function of the frequency. An accurate measuring capsule should have a frequency response that is as linear as possible, i.e. no significant distortions or resonances in certain frequency ranges.

2. Sensitivity: The sensitivity indicates how well the measuring capsule is able to convert acoustic signals into electrical signals. It is usually given in millivolts per Pascal (mV/Pa). An accurate measuring capsule should have a high sensitivity in order to detect even quiet sound sources.

3. Directional characteristic: The directional characteristic indicates how the sensitivity of the measuring capsule varies depending on the direction of the sound. An accurate measuring capsule should have a directional characteristic that is as uniform and reproducible as possible.

4. Distortion factor: The distortion factor indicates the extent to which the measuring capsule generates non-linear distortions of the recorded signal. An accurate measuring capsule should have the lowest possible distortion factor in order to enable accurate and undistorted recording of the sound.

The accuracy and precision of a measurement microphone capsule is usually evaluated on the basis of these parameters and by comparison with reference values or standards. There are also special test procedures, such as calibration according to international standards (e.g. IEC 61094-4), to evaluate the performance of a measuring capsule.

When using measurement microphone capsules in different environments, various challenges can arise, especially at high temperatures or in humid environments. Here are some of the most common challenges:

1. Temperature: High temperatures can affect the performance and accuracy of the measuring microphone capsules. The electronic components can overheat and change their sensitivity or frequency response. It is important to choose microphone capsules that are designed for use at high temperatures and have good heat dissipation.

2. Humidity: In a humid environment, moisture can penetrate the microphone capsule and damage the electronic components. This can lead to reduced sensitivity, distortion or even failure of the microphone. It is important to use measurement microphone capsules that are protected against moisture and may have an IP rating to minimize water ingress.

3. Dust and dirt: In environments with a lot of dust or dirt, particles can get into the microphone capsule and impair sensitivity or sound quality. Good sealing of the capsule can minimize the ingress of dust. It may also be advisable to carry out regular cleaning and maintenance to preserve the life and performance of the microphone.

4. Vibrations: In environments with strong vibrations, such as near machinery or in vehicles, the microphone capsules can pick up unwanted noise or distortion. It is important to choose microphone capsules that have good vibration damping or can be mounted in a stable mount to minimize these problems.

5. Electromagnetic interference (EMI): In environments with strong electromagnetic fields, such as near high-voltage power lines or electronic devices, microphones can pick up interference or unwanted signals. It is important to choose microphone capsules that are shielded against electromagnetic interference to ensure the accuracy and quality of the measurements.

It is important to consider the specific requirements of the environment and choose microphone capsules that are suitable for these conditions to ensure accurate and reliable measurements.

There are currently various developments in the field of measurement microphone capsules that rely on new materials and technologies. Some examples are:

1. MEMS technology: MEMS (Micro-Electro-Mechanical Systems) are small mechanical and electrical systems at micro level. MEMS microphones use tiny silicon structures to convert sound into electrical signals. This technology enables a compact design and high sensitivity.

2. Electret capacitors: Electret condenser microphones use a permanently polarized diaphragm to convert sound into electrical signals. Current developments focus on improving the sensitivity, noise suppression and frequency response of these microphones.

3. New materials: Research and development focuses on the use of new materials for the diaphragms in microphone capsules. For example, graphene, a single-atom layer of carbon, and other nanomaterial-based membranes are being investigated to improve the sensitivity and bandwidth of the microphones.

4. Directional characteristic: Current developments are also focusing on improving the directional characteristics of microphone capsules. Work is being carried out on technologies that make it possible to adapt the directionality of the microphone to the respective application, for example by electronically controlling the directional characteristic or using special diaphragm structures.

5. Miniaturization: The trend is also moving towards ever smaller and more compact microphone capsules. This enables use in devices such as smartphones, headphones or wearables, where space and weight play a decisive role.

These developments are aimed at improving the performance and versatility of measurement microphone capsules and adapting them to different applications.