TABLE 2. Theshold for perception of rf sound (ambient noise level 70-      
         90 db).                                                           
                                                              Peak         
                                 Avg        Peak     Peak    Magnetic      
                                Power      Power   Electric   Field        
Trans-   Frequency,  Duty Cy.  Density,   Density   Field      amp.        
mitter      mc                 mw, cm2    mw, cm2   v cm     turns, m      
                                                                           
  A       1,310      .0015      0.4         267      14         4          
  B       2,982      .0004      2.1       5,250      63        17          
  C         425      .0038      1.0         263      15         4          
  D         425      .007       1.9         271      14         4          
  E         425      .014       3.2         229      13         3          
  F         425      .028       7.1         254      14         4          
                                                                           
                                                                           
FIG. 4. Threshold energy as a function of frequency of electromagnetic     
        energy (ambient noise level 70-90 db).                             
                                                                           
        10000|---------|-------------|--------------|                      
             |---------|-------------|--------------|                      
  PEAK       |---------|-------------|--------------|                      
  POWER      |---------|-------------|-------------*|                      
  DENSITY    |---------|-------------|------------*-|                      
  (mw/cm2)   |         |             |          *   |                      
             |---------|-------------|---------*----|                      
             |         |             |       *      |                      
             |---------|-------------|------*-------|                      
             |         |             |    *         |                      
             |         |             |   *          |                      
             |         |             | *            |                      
         1000|---------|-------------*--------------|                      
             |---------|-----------*-|--------------|                      
             |---------|---------*---|--------------|                      
             |         |       *     |              |                      
             |---------|-----*-------|--------------|                      
             | * * * * * * *         |              |                      
             |---------|-------------|--------------|                      
             |         |             |              |                      
             |         |             |              |                      
             |         |             |              |                      
          100|---------|-------------|--------------|                      
            200       1000          2000           3000                    
                        FREQUENCY (mc)                                     
                                                                           
                                                                           
                                -37-