The term 'ROCK CONCERT BLASTER' is composed of three words, each with a corresponding crossword solution. The first word, 'ROCK, ' is solved by the three-letter answer 'AMP, ' which stands for 'AMPLIFIER.' An AMPLIFIER is an electronic device used to increase the volume of sound coming from a SPEAKER or microphone. The second word, 'CONCERT, ' is solved by the four-letter answer 'GIG, ' which is a slang term for a live performance. The third word, 'BLASTER, ' is solved by the seven-letter answer 'SPEAKER, ' which is a device that converts electrical signals into sound waves. Together, these three solutions form the phrase 'ROCK CONCERT BLASTER, ' which refers to a powerful sound system used at ROCK concerts.