So, these (& similar) Android app give audio on the event:
1. "Scanner Radio" app offers a list
- sorted by number of listeners -
of available online scanners, ie,
around USA & the world.
When I chose Boston police, fire, etc.
from that list (of course, it held top-place),
there were over 50,000 others listening-in.
Normally, numbers of listeners - across
the list - are under 500.
(If your area lacks an online-connected
scanning receiver & your have such a
receiver & some bandwidth to share,
why not consider adding your area's
emergency services audio to the list?)
2a. "TuneIn [Pro]" app is (yet another)
Internet Radio app; [Boston Univ Radio's]
WBUR stayed on the story -continuously-
from shortly after the event became known.
2b. Using the same app, one can get cur-
rent weather and detailed forecasts, also
on a continuous basis, from USA Weather
broadcasters (commercial-free, these are
available 24x7 - to those near the area of the
event - on 10 VHF channels near 162 MHz);
Boston's gov't weather station was available
via TuneIn (Search "By location" for Boston
for a list of all broadcasters - AM / FM / Wx,
including some located in nearby states).
3. "EchoLink" app - for Radio Amateurs -
let licensed Hams listen to & (in normal times)
even transmit on repeaters - most on 2m VHF
(around 146 MHz) & 70cm UHF (near 440 MHz)
- that would become active, especially when an
event (flood, earthquake, etc.) takes out normal
POTS or cellular phone & 2-way radio comms.
(If you're a Radio Ham, you can add your own
station (eg, home, office or vehicle radio) or
your club's repeater to the list. Whenever you
sign-in, you're on one of the lists, so friends
can contact you, on the fly. Also, EchoLink is
like an old-time phone-echange switchboard,
ie, able to connect repeaters, etc. together, eg,
to support relief operations after a larger dis-
aster or - during peaceful times - just a yacht-
or bike-race, etc.)
These apps work on Android phones & tab's
2.2 thru 4.1.2, in my experience. Of course,
YMMV.
I don't know what app's may be available for
iPhone, etc.