How to Evaluate the Quality of a Wireless Microphone System
Although operating wireless microphone systems can sometimes be complex, there are simple tests (without specialized equipment) that provide valuable insights into the core performance of a wireless microphone, offering significant practicality. By definition, a wireless microphone remains a "microphone." Its sole design objective is to produce accurate audio signals for various applications. The term "wireless" signifies its ability to function without a physical connecting cable. Before deciding to purchase or rent a system, it is advisable to conduct the following tests to help you assess the quality of a specific wireless microphone system. Each test examines a particular type of system performance or potential issue. For a comprehensive quality assessment, perform as many of these tests as feasible, as you may find certain designs excelling in one area while performing poorly in another. Relying on only one or two tests is insufficient for a thorough overall evaluation.
1. "Car Keys Test"
This is a popular test among high-end wireless manufacturers. This simple test reveals how effectively a wireless microphone handles high-frequency audio transients while reflecting the quality of the entire audio processing chain. Connect headphones capable of fully shielding feedback at very high SPLs or an audio system to the wireless system. Ideally, use headphones or a system allowing focused listening to the receiver's audio output while isolating the original sound of the jingling keys. Set the transmitter's input gain to a normal level based on average speaking volume. Gently shake a key ring close to the microphone to produce jingling sounds. Shake the keys about one foot from the microphone, then slowly move farther away while shaking until you are 8 to 10 feet away. Listen to the audio emanating from the receiver. Does it sound like keys jingling or a crushed bag of potato chips? Next, have someone speak into the wireless system while you shake the keys. Listen for distortion in the speaker's voice. Repeat the test with the keys held one foot away, then 8 to 10 feet away, noting the effects on the speaker's voice.
This is a very challenging test for any wireless microphone except one connected by a wired cable. The results you hear will indicate whether the design's input limiter and compander exhibit excellent attack and release times, providing insight into the real-world audio quality achievable. Loosely swinging metal keys on a ring generate numerous high-frequency transient sounds. Systems failing this test often distort sibilant sounds ('s', 'sh') in vocal applications. Listeners may not readily notice this high-frequency transient distortion because sibilance lacks specific frequency points, resembling random noise more. Distorted random noise still sounds like noise, making detection difficult.
However, in this key test, many failing wireless microphones output audio where the crisp key jingles sound muddy at the receiver, akin to someone cupping their hand over the microphone. The key test prompts you to listen carefully for any distortion. It also reveals audio circuits disrupted by ultrasonic frequencies. The peak energy of crisp key sounds actually centers around 30kHz, above human hearing. If circuits in the transmitter fail to filter out these ultrasonic frequencies, the compander will react erroneously. This is a relevant test because sibilant sounds in vocals also contain ultrasonic components. Sounds you cannot hear can cause erratic level fluctuations; ultrasonic overload will make sibilance sound harsh.
1. "Car Keys Test"
This is a popular test among high-end wireless manufacturers. This simple test reveals how effectively a wireless microphone handles high-frequency audio transients while reflecting the quality of the entire audio processing chain. Connect headphones capable of fully shielding feedback at very high SPLs or an audio system to the wireless system. Ideally, use headphones or a system allowing focused listening to the receiver's audio output while isolating the original sound of the jingling keys. Set the transmitter's input gain to a normal level based on average speaking volume. Gently shake a key ring close to the microphone to produce jingling sounds. Shake the keys about one foot from the microphone, then slowly move farther away while shaking until you are 8 to 10 feet away. Listen to the audio emanating from the receiver. Does it sound like keys jingling or a crushed bag of potato chips? Next, have someone speak into the wireless system while you shake the keys. Listen for distortion in the speaker's voice. Repeat the test with the keys held one foot away, then 8 to 10 feet away, noting the effects on the speaker's voice.
This is a very challenging test for any wireless microphone except one connected by a wired cable. The results you hear will indicate whether the design's input limiter and compander exhibit excellent attack and release times, providing insight into the real-world audio quality achievable. Loosely swinging metal keys on a ring generate numerous high-frequency transient sounds. Systems failing this test often distort sibilant sounds ('s', 'sh') in vocal applications. Listeners may not readily notice this high-frequency transient distortion because sibilance lacks specific frequency points, resembling random noise more. Distorted random noise still sounds like noise, making detection difficult.
However, in this key test, many failing wireless microphones output audio where the crisp key jingles sound muddy at the receiver, akin to someone cupping their hand over the microphone. The key test prompts you to listen carefully for any distortion. It also reveals audio circuits disrupted by ultrasonic frequencies. The peak energy of crisp key sounds actually centers around 30kHz, above human hearing. If circuits in the transmitter fail to filter out these ultrasonic frequencies, the compander will react erroneously. This is a relevant test because sibilant sounds in vocals also contain ultrasonic components. Sounds you cannot hear can cause erratic level fluctuations; ultrasonic overload will make sibilance sound harsh.