I just heard Priscilla's audio training on WAN Troubleshooting and I think it's great. I spent the time listening to the audio file while organizing my desk at work; very convenient!!. I'd definitely pay for audio training if it was available.
Priscilla, do you have any other audio training files besides WAN Troubleshooting? ""John Neiberger"" wrote in message news:[EMAIL PROTECTED].; > I know that I like this sort of product and I wish I'd had more of this > sort of thing available when I first started out in this field. For > certain types of learners, hearing someone discuss the topic allows it > to sink in better than reading alone. I'm definitely that type of > learner. > > One problem I've seen with some audio-based training is the pricing. > IMO, they are often priced too high. While audio training is quite nice > to have, it's not necessarily as portable as books, for instance, > although that is changing quickly. Pretty soon everyone will have a > portable MP3 player and/or CD burners and they'd easily be able to go > mobile instead of sitting glued in front of their PCs. > > Regards, > John > > >>> "Priscilla Oppenheimer" 3/1/02 1:15:08 PM > >>> > Speaking of sample rates, I am playing with the idea of offering audio > > training using MP3 files. I have prepared such a training on WAN > Troubleshooting. I'd love to get some feedback. This audio training > will > help people studying for the Support test especially. It's 40 minutes. > This > means the file is huge, so don't try this at home on a modem line. The > file > is available for download here: > > http://www.troubleshootingnetworks.com/audio.html > > Please send me some feedback. Would you find such a product line > helpful? > Would you pay for MP3 audio training files? > > Thanks. > > Priscilla Oppenheimer > > > > > > At 03:32 PM 2/27/02, John Neiberger wrote: > >Yes, this was very distracting! :-) I didn't get any studying done > at > >all last night! Between checking and answering email, looking for > >Clannad MP3s, reading about the Gaelic language just for fun, and > >looking up telecom stuff it's a wonder I even powered up a router. I > >was able to boot up six routers, erase their configs, and recable > them > >in preparation for a lab scenario tonight. Not bad for three hours > >work. heh heh... > > > >Thanks, > >John > > > > >>> "Priscilla Oppenheimer" 2/27/02 3:04:13 PM > > >>> > >Female opera singers probably hate it when people ask them to sing > over > >the > >phone!? > > > >OK, have we distracted you enough, John? ;-) Seriously, I think this > >was a > >great discussion. Thanks to everyone who contributed. > > > >Priscilla > > > >At 10:58 AM 2/27/02, David L. Blair wrote: > > > > John Neiberger wrote: > > > > What I'm trying to find out is why the original 4KHz limit on > > > > voice calls was put into place. It sounds like it was simply > > > > an arbitrary decision. 4KHz is sufficient for a telephone call > > > > and to provide clear calls that included higher frequencies > > > > might have added some technical complexities, perhaps. > > > > > > > > They also added a high-pass filter around 400Hz since most > > > > telephones can't reproduce low frequencies well and it also > > > > filters out some harmonics of 50-60Hz hum that might show up > > > > from time to time. That is concrete reason for including a > > > > high-pass filter and I wondered if there was a concrete > > > > technical reason for including the 4KHz low-pass filter. From > > > > the sounds of it there really isn't a technical issue, 4K is > > > > just a nice round number. :-) > > > > > >I used three sources to answer John's query: "Voice over IP > >Fundamentals", > > >"Cisco Voice over Frame Relay, ATM, and IP", and Integrating Voice > and > >Data > > >Networks". These are great books for anyone wanting to know more > >about > > >voice technologies. > > > > > >Interesting Facts and Ideas I came across: > > > > > >1) Human hearing is in the range of 200 Hz to 20,000 Hz > > > > > >2) Human speech is in the range of 250 Hz to 10,000 Hz. Most of the > > >information comes from the middle frequencies. According to > Nyquist, > >"Human > > >voice contains sounds that are more often Middle-pitched > frequencies > >than > > >either High or Low pitched frequencies. > > > > > >3) Frequencies greater than 4,000 Hz are filter out to limit > >crosstalk. > > > > > >4) During the Analog to Digital conversion voice samples are put > >though a > > >process called Quantization. Quantization is the process of > rounding > > >sampled values to the nearest predefined discreet value. Pulse Code > > >Modulation (PCM) is a Quantization process. PCM is also used to > >achieve 12 > > >to 13 bits of voice information in 8 bit words. Two commonly used > >PCM's are: > > >mu-law (North America), and a-law (Europe). What you hear is not > >someone's > > >voice, but a representation of their voice. > > > > > >5) Noise is a major issue when talking about voice quality. Noise > is > > >constant problem for Analog signals. What is signal and what is > >Noise? > > >When a Analog signal is amplified so is the Noise, which in turn > makes > >the > > >quality of Analog calls worst as the distance increases. Digital > >Calls are > > >less suitable to Noise than Analog calls. > > > > > >6) Delay is a major issue when talking about conversation flow for > >two > > >reasons: 1) For a conversation to flow normally, the delay is > >receiving the > > >voice information must be less than 250ms. When the delay is more > >than > > >250ms, the human receiving the voice message will start to talk > >thinking the > > >human sending the voice message is at a breaking point in the > >conversation, > > >i.e.. both people are talking at the same time similar to a > collision > >in > > >Ethernet. Delay is also important in how the voice packets are > >filled > > >during the Analog to Digital conversion. That is why ATM (ATM cell > is > >53 > > >octets, 5 octets are header and 48 octets are payload) is a good > >method for > > >transporting voice packets because the delay to fill the payload > >section is > > >smaller than with other cell/packet types. > > > > > > > > >Answer: It does indeed seem that the 4,000 Hz mark was arbitrary in > >nature; > > >3,500 Hz or 5,000 Hz would work also. It is a "nice round" number > to > >work > > >with. Simplies any math work. Middle frequencies carry the bulk > of > >the > > >information and Human speech upper limit is 10,000 Hz amd 4,000 is > >near the > > >middle. The low filter is also to reduce the frequencies that carry > >less > > >information. > > > > > >Hope this helps. > > > > > > > > >"Through Complexity there is Simplicity, > > > Through Simplicity there is > >Complexity" > > > > > >David L. Blair - CCNP, CCNA, MCSE, CBE, A+, 3Wizard > >________________________ > > > >Priscilla Oppenheimer > >http://www.priscilla.com > ________________________ > > Priscilla Oppenheimer > http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=37028&t=36566 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
