Once again, we have the presence of five primary character archetypes at work in a story:

Protagonist: Ruby.

Attractor: Miles. A traditional love interest, but a secondary storyline, not a conventional Big Romance. Her real "romance" is with singing.

Mentor: Bernardo (music teacher), Leo (brother). The former is the Outsider who pushes her to go inside herself and "claim" the right to be a singer. He helps her find her voice (think Lionel in The King's Speech who has a similar role in relation to Bertie, the man who would be king). The latter is the Insider (family member) who provides support for Ruby to leave the "nest."

Tricksters: Frank, Jackie (parents). I like to think of the Trickster as a shapeshifter, switching from ally to enemy, enemy to ally. In this case, if we look at Ruby's goal -- go to Berklee -- then her parents, especially Frank, are enemies for much of the movie. Eventually, they become allies in supporting Ruby's desire to go to Berklee and pursue her passion for singing.

Which leads us to this: Who (or what) is the Nemesis? I would argue it is deafness. The bottom line narrative function of a Nemesis dynamic is to provide opposition to the Protagonist and their goal. In this case, deafness does that in at least two ways: (1) The fact her parents and brother are deaf requires Ruby, who can hear, to be a part of the family fishing business. Not only a part, but a major role in conducting transactions with the hearing world. This dynamic is what "enslaves" her to the Parent Path, the path of what she feels like she should do, and in so doing curtails the desire to pursue her personal dreams. (2) Deafness prevents her parents from hearing Ruby sing. If they could hear their daughter's singing voice, I would imagine they would wholeheartedly support her creative ambitions. They would also not need Ruby to act as an intermediary with hearing customers.

There's also a third way deafness works against Ruby's goal, more metaphorically and that is Ruby refuses to "hear" the call she has inside, to pursue her dreams of being a singer. It's like an imposed deafness she has (originally) which she has to lose in order to hear and embrace her own Inner Voice.

One final thought: As I've been typing my comments, I have consistently had a hard time typing "sing" as it has been coming out as "sign." I doubt anybody involved in the writing and producing this movie thought anything of this, but it's an interesting way to think of Ruby's arc, going from:

signing --------------->>>>>>>>>------- singing

More on that when we discuss Themes.