I have told the glad news of deliverance in the great congregation;
see, I have not restrained my lips, as you know, O LORD.
I have not hidden your saving help within my heart,
I have spoken of your faithfulness and your salvation;
I have not concealed your steadfast love and your faithfulness
from the great congregation.
- Psalm 40.9-10, NRSVI once visited a congregation which made frequent use of thoughtfully prepared congregational responses (often what people mean when they refer to a service as "liturgical"). I joined in reciting the responses in what I considered a regular voice, pitched for the size of the room and the number of people. As is often the case, many of the congregation spoke the lines almost under their breath. After the service, I was quietly admonished by one regular congregation member who informed me that he found my volume distracting. I realise that speaking together is a skill that can take some practice to work well, but I was somewhat at a loss at this response. Apparently, he wasn't commenting on my adopting an unusual rhythm or strange emphasis, merely the fact that others could hear what I said.
Communal responses, though often addressed to God in prayer, are just as frequently exhortations addressed to one another. I've always assumed that if we're going to use them (and I think they are excellent when done well, for all kinds of reasons), then we may as well not pussyfoot around. In such situations, I'm not just speaking to myself, or even to my neighbour, but am addressing (and hope to be addressed by) the congregation.
And so when the opportunity to speak of God's faithfulness and salvation amongst the congregation arises (whether in song, liturgical response, testimony, public prayer, scriptural reading or whatever), don't be shy. Open your lips and speak up!