ST150 1-line Amplified Business Speakerphone is a sophisticated amplified business speakerphone that can digitally adjust frequency-specific volume levels so that any user, especially those working in extremely noisy environments, can comfortably and clearly hear a caller's voice. It boasts highly flexible sound settings: incoming voices may be amplified by up to 52 dB with extra amplification for high frequencies. This level of amplification has been tuned to more effectively restore the perception of many phonemic distinctions common in speech than competing models. Your colleagues won't know you have hearing loss. This phone looks exactly like a normal business phone, when you increase volume it adds frequency-specific amplification automatically.