Final answer:
Without specific medium properties or empirical data, the attenuation coefficient in soft tissue at a frequency of 12 MHz is approximated using the rule of thumb as 6 dB/cm.
Step-by-step explanation:
The question pertains to calculating the attenuation coefficient when a sound beam is traveling in soft tissue, with a given frequency of 12 MHz. The attenuation coefficient is typically presented in units of dB/cm in medical ultrasound applications. However, the question provided does not contain enough information to directly calculate the attenuation coefficient because it typically requires knowledge of the medium properties or empirical data. In the context of medical ultrasound, the rule of thumb is that for soft tissue, the attenuation coefficient (α) in dB/cm is approximately equal to half the frequency in MHz. Thus, for 12 MHz, this rule would suggest an attenuation coefficient of 6 dB/cm.