Examples of enhanced synesthesia

Emma sees flashes of light when water drips...

...a flurry of light when a mug crashes to the floor...

...and continuous waves of light when a cellist plays a song.
(Ink)

When the cellist leaves, Emma plucks the cello's strings, seeing more streams of light...

...then decided to try to play herself.
(Ink)

Emma sees a police siren emitting red waves of light...

...as well as yellow ones...

...she also sees beams of light when a jackhammer is turned on.
(Hysterical Blindness)

Peter kicks a can and sees color when it creates sound...

...he also sees the sound created by a young choir.
(Hysterical Blindness)

When Emma and Peter play the piano together...

...beautiful colors are produced.
(Hysterical Blindness)

While playing the cello again...

...Emma's light waves crash against the wall...

...and when Emma begins to play uncontrollably...

...the light waves cause the wall to shatter.
(Hysterical Blindness)

Emma sees the flurries of light created by the children's applause...

...and reaches out to them when time is stopped.
(Tabula Rasa)

Through her ability, Emma plays the piano...

...skillfully and beautifully.
(Tabula Rasa)

Emma returns to the piano to practice her ability.
(Shadowboxing)

Emma plays the cello in Central Park...

...creating a flurry of colors...

...which draws towards her an audience...

...including Ian Michaels, on whom Emma is concentrating while playing.
(Upon This Rock)

Emma plays the cello and focuses her thought on Peter Petrelli...

...and soon, Peter shows up at her door.
(Close to You)

Under Doyle's control, Emma plays the cello...

...attracting a large crowd to the Sullivan Bros. Carnival.
(Brave New World)

When Doyle's grip loosens for a second, Emma lashes out...

...striking Doyle with a sound-wave.
(Brave New World)

Chris Coolidge uses his power...

...to attract people to Uncle Ira's.

Even inside, Chris uses his power.

Then, Chris uses his power to stop the police.
(From the Files of Primatech, Part 1)