Microphones - the most popular sound sensors
Microphones are sensors operating on the principle of proportional conversion of the energy of the mechanical vibrations of the magnetic diaphragm into electricity, in the form of a voltage causing the current flow in the coil winding. The most common microphone designs used on stage and in recording studios are dynamic, ribbon and condenser microphones. In addition to popular microphones, sound sensors based on piezoelectric and electrostatic phenomena are also used, which enable sound detection in various industrial, medical and robotics applications, as well as in identifying and tracking objects, e.g. by echolocation. The design of such sensors allows the detection of sound waves, the frequencies of which fall outside the spectrum of the human audibility band. For example, ultrasonic sensors are used in the process of welding plastics, and infrasound sensors are used in the process of inspecting the structure of materials with a lower density than most metals, such as wood, concrete or cement. Measurements made with such sensors are not affected by environmental illumination, as can be the case with measurements with light intensity and colour recognition sensors.
Buzzers - one of the smallest speakers with a wide range of applications
The buzzer is a small loudspeaker that produces a clear sound signal by applying a voltage to its terminals. Most often, the design and operation of a buzzer are based on the vibration of piezoelectric material between two electrodes. For the buzzer to generate sound, its electrodes should be fed with a voltage that changes in time, e.g. in the form of a PWM signal from the microcontroller output. Buzzers are used in all applications that require sources of a simple acoustic signal, such as microwave ovens with sound signalling of the end of heating a meal, alarm and warning devices, as well as electronic toys. Buzzers are also found in PC desktops and make themselves felt, among others when the user warns about enabling the Sticky Keys function. Thanks to their small dimensions and low energy consumption, they are also used in playing gift cards.
Grove - high-quality sound level sensors
The sound level sensors are designed to measure ambient sound pressure levels. The built-in electret microphone and operational amplifier adequately filtering the input signal from interference (the bandwidth depends individually on the model) and the potentiometer for adjusting the gain of the output signal from the sensor (applies to the model based on the LM2904 chip), enable precise calibration and use of these sensors in sensory applications for sound detection and measuring its parameters. The sensors are compatible with Arduino - their output receives an analogue signal in the form of voltage. The sensor output should be connected to the input of the analogue-to-digital converter in Arduino, while in purely hardware applications, the purpose of which is to detect sound with a threshold amplitude, the sensor should be connected to one of the comparator inputs or an operational amplifier operating in the window discriminator mode.