In Tune With Technology Digital Musical Tuners

What is its Purpose? Instrument tuners indicate whether the pitch of a specific note being played is sharp, flat, or in tune with the standard. Tuners most often use the A above middle C for comparison, which has a frequency of 440Hz (440 wavelengths per second).

A digital tuner contains the following: A microphone An A/D converter Signal Processing An LCD screen

The Microphone (Specifically, the Condenser Microphone) The condenser microphone uses a capacitor (a device used to store an electrical charge) to measure sound waves. There are two sides to the capacitor: a negatively charged back plate and a a positively charged, flexible membrane. As sound waves hit the membrane, it vibrates, varying the distance between it and the back plate. The resulting current is proportional to the displacement of the membrane.

A/D Conversion –An analog-to-digital converter is an electronic device that produces a numerical value for every input of voltage. –Voltage is the potential difference between two charges. As the voltage from the converter changes, its magnitude is converted into a digital number.

Signal Processing Audio signal processing is the interpretation of auditory signals. As the sound waves are being converted to binary numbers, digital signal processing uses the methods of sampling and quantization to reduce continuous signal of the wave into a set of finite, approximated integer values. The numerical values are used to determine the sound’s pitch, or freqeuncy.

LCD Screen LCD stands for liquid crystal display. Each LCD pixel has a layer of liquid crystal molecules, twisted between two perpendicular electrodes (electrical conductors), which are between two polarized filters with perpendicular axes of polarity.

How an LCD screen works When there is no electric current, light coming through the first filter is twisted by the crystal helix, allowing the light to pass through the second filter and bounce back off of a reflector in the back. The screen appears light. As an electric current is sent across the electrodes, the crystals align with the current. The light is not twisted, and is completely blocked by both of the filters. The pixel then appears black.

The Final Product With all components put together, the result is a digital device that will detect the sound waves of a musical note with a microphone, analyze the frequency as a digital number, and display the pitch compared to what it should be on an LCD screen. Musicians then tune their instruments accordingly.