R' Shraga Feivel Mendlowitz would explain that each of the instruments mentioned in the final chapter of Tehillim with which to praise Hashem—shofar, harp, flute among others—arouses a different emotional response: one arouses tears while another arouses happiness and another encourages deep reflection. Taken as a whole, the message is that one must serve Hashem with every emotion.
The chapters of Tehillim were intended to be sung with musical accompaniment. In fact, each chapter had its own designated instruments and melody so that they would elicit the desired thought, comprehension and emotions that Dovid Hamelech sought to evoke with that particular passage. The Redak writes “It was with instrumental accompaniment that the songs, melodies and praises were ‘said,’ each one according to its tune, which was known to them. It was a great wisdom and it was to arouse the wise soul.”
Building on the Redak’s words, R' Matisyahu Solomon cites the words of a certain old man: “One can never fully understand a chapter of Tehillim with clarity until one knows this wisdom, and understands and recognizes the distinct sounds of the musical instruments and how each specific instrument fits a specific paragraph unlike any other. For it is the musical instruments and the tune that gives the requisite flavor and understanding to comprehend the matters with their desired depth.”
