Section 19 Measure Sound Volume 
    
The volume we speak at is something we take for granted. Most of us have the self-awareness to the point we can talk at a level that people will not hear across the room. Anyone could speak too loudly. For some with autism or speech disorders, this can be a real issue. One way to teach this is with feedback. That does not mean you just scold someone. With these simple apps, you can give a quantitative number that illustrates just how loud they are. Then a student can practice talking lower and see the difference based on a measured number. 
iPhone/iPad
    
      Decibel X - dBA Noise Meter
    
This is a very good free sound meter. 
    
Decibel X PRO: dBA Noise Meter
This is a paid version of a good sound meter app. 
    
      
    
    
      Decibel : dB sound level meter
This is an inexpensive sound meter with some very good reviews. You can also make some in-app purchases.
Voice Meter Pro
This is a sound meter that you have to pay a small fee to buy. However, the app is very good and worth the money if you use it on a regular basis. 
      
    
Google Play Apps
    
      Sound Meter dB
    
This is a very good sound meter from the Google Play Store. 
    
    
   
  
    Sound Meter - Decibel meter & Noise meter
This is a sound meter app that gets some good reviews.