25. Two sound sources each produce sound of frequency 500Hz. One is at the origin and the other is moving at a constant speed of 10% along the xaxis. The speed of sound in air is 340%. An observer at the origin hears beats between the two sounds. When the moving sound source is moving away from the observer, what best describes the beat frequency, as compared to when it is moving towards the observer? (a) fbem; = 15.2Hz and the beat frequency is higher than when the source was moving towards the observer. (b) fbem; = 15.2Hz and the beat frequency is lower than when the source was moving towards the observer. (c) fbeat = 14.7Hz and the beat frequency is the same than when the source was moving towards the observer. (d) fbeat = 14.3Hz and the beat frequency is higher than when the source was moving towards the observer. (e) fbwt = 14.3Hz and the beat frequency is lower than when the source was moving towards the observer