Application to measure frequency ?

[Externet]

Hi.
Is there an application for an Android phone you may suggest that can tell by sound the frequency Hz (cycles per second) of a noise ? Would like to find the RPS (Hertz) or RPM (multiplying by 60) of an air compressor.
Seen several applications listed but none convincing; seem more automotive oriented, with selection of 4,6,8 cylinders, 2, 4 strokes...

 

[billybob]

I’ve wondered that myself that would be very helpful for experiments with resonance!

 

[billybob]

Could probably whip something up with a arduino

 

[rjenkinsgb]

There are many "guitar tuner" type apps, that will display the frequency of a tone.
The limitation may be the low frequency response of the phone mic..

 

[Visitor]

This one for Android is decent.

Keep in mind with machinery vibration (and therefore airborne noise) that there will be tones at more than shaft rate (rotation rate).

Some examples:

0.4–0.5× excessive clearance in sleeve bearings
1× balance and/or alignment
2× alignment

Non‐integer peaks between ~1× – ~10× rolling element bearing deterioration

Forcing frequencies – number of elements such as:

Fan blades
Pump impeller blades
Motor rotor bars
Gear teeth

× rotation speed


Reciprocating machines with have many strong harmonics of shaft rate.