There's no real incentive to make any noise for the player to actually trigger the monsters to come. If they actually swam around under your boat I'd at least feel some kind of tension. If there were jumpscares or audio scares, maybe the player might scream? The only category of players actually affected by this mechanic, if we ignore hardware limitations, would be people talking over the game, so not your average player. It would also be nice for it to clarify that it's actual user volume and not in-game volume because I thought at first that the noise level was based on the fish-catching noise and not me making noise, so I sat there thinking "why is nothing happening besides fish". Funnily enough, my earbuds' mic is broken so I had to plug in my actual mic for this to actually view the game over screen by pspspspsps-ing the spooky fish for an extended period of time like it was a cat. I think it was worth it- the monster fish designs are nice. Overall, the concept's there, just not very well executed.