Which factor can cause ultrasonic sensors to misread signals due to noise?

• A. Humidity
• B. Electromagnetic interference
• C. Ultrasonic noise from mechanical equipment
• D. Low battery

Answer: (C)

Ultrasonic sensors work by sending a pulse and listening for its echo to determine distance. If there’s acoustic energy in the ultrasonic range in the environment, it can be picked up as additional echoes or create a confusing signal, leading to a misread. Mechanical equipment like motors, pumps, or fans often emits ultrasonic noise, which travels and interferes with the sensor’s received signal, causing false readings or missed echoes.

Humidity can affect how sound travels by attenuating it slightly, but it doesn’t add interfering noise in the same way. Electromagnetic interference targets the sensor’s electronics rather than the acoustic path, so it’s less about noise in the sound channel. A low battery may weaken the signal, but the problem described—misreading caused by noise in the signal—points to ultrasonic noise from mechanical equipment as the direct culprit.